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I'd like to address one of my concerns regarding multiline TRL calibration. After calibrating a frequency, I occasionally did not get the expected result. If you look at my attachment, you'll notice that after calibration in some frequency ranges, it shows a sharp curve above 0dB (sometimes). Is there anyone who can say me why this type of error occurred?
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This is the typical signature if a bad contact (loose connector) somewhere in your setup
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I do not have anything to test but if you can point me in the right direction? Looking for what is the relative permittivity for the Felt fabric?
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Dear Meenakshi
Please, see the following reference. It is a study about many wearable material parameters:
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Hi, I am trying to perform mesh convergence and I found out there is no stable temperature value I obtained. So, I calculated the skin depth and it was around 0.00011mm. It is so small in micrometer level while my tool is of 5mm thick in 2D. How can I mesh for such a low value? I tried but the temperature is still not stable and temperature varies and not stable. Can someone help me overcome this situation. You can see the picture attached below. A coil is placed above the tool alone at a certain distance. I am unable to proceed. Any help or suggestions would be nice. thank you :)
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I hope to find the answer in the following pdf
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I am trying to design a CPW-GCPW tapered transition. Can anyone recommend a book or a reference for these types of transition structures? (Like how to calculated the tapered length etc.)
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The catch for the design of such kind of structures is the right combination of protein and silicon computers; the silicon computer in genal will not tell you the shape you should use..but once you have a shape in mind you can nicely analyze it in great detail which is not to easy for the protein computer (your brain); there are many books which discuss tansitions of all kind..but the gernal rule it..avoid sharp steps and try to implement for or less smooth transients from one cross-section to another...use you intuition there...and then ask he silicon computer jow he likes this.
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My computer suddenly restarted itself. Then I can't read/open my most recent working project? Is it possible to read/open it? It is very important to open this file. I've attached a screenshot of the error. Thank you in advance..
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Contact ANSYS support, They can give you better guidance, possibly without loosing your file and data.
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I've included an example picture. Is this transition followed by Quarter Wave transfer rules? or, Can anyone assist me in properly identifying this transition section?
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You should know that this is not governed by quarter wave transition rules. A quarter wave transformer transforms between two different impedances not two impedances that are the same. The flare will introduce an effective lumped capacitance at the join and may be to compensate for other parasitic inductance or capacitance at the transition.
It probably isn't, but it may just be a badly designed transition. Not everything in published papers is good, especially if that wasn't the main point of the paper.
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I am actually feeding the spiral from the edge. so, at the end of one spiral arm, I have a feed. impedance matching I am not worried about right now. Now, I am trying to get a 180 deg phase shift. I am stuck how to do that. I have already tried wilkinson power divider. It did not work. Please advise. I will really appreciate. Thank you.
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Hi
for applying phase differences in the spiral antenna generally use a compact feed network with a Wilkinson power divider. You can also use the following articles:
“Square-spiral antenna with unbalanced-excitation”
"Wide-beam spiral antenna with three folded arms fed by compact three-way Wilkinson power divider"
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In the circular monopole antenna with partial ground plane is there to make it ultra wide band or match the impedance of circular patch?
Please clear this confusion for me? Because, usually, we do inset feed to match the impedance. here we are not doing inset feed but edge feed. so, the purpose of partial ground plane is just to increase the bandwidth of antenna or to match the impedance as well?
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If this is a monopole then it is quarter wave resonant. You usually see matching slots in microstrip patches, which are half-wave resonant, however slots could still be used here to change the match.
Making the monopole round increases its bandwidth compared to a thin wire monopole. Thick monopoles have a wider bandwidth than thin monopoles. The shape of the ground changes both the match and the bandwidth, usually the match determines the bandwidth so changing one changes the other.
This is not a microstrip patch with a partial ground, it is a monopole fed from microstrip, with an edge ground rather than a flat ground perpendicular to the monopole.
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So, if I have data of one linear polarization and then 90 deg to the first polarization. How can I calculate these two amplitudes and phases so that it will be right hand circular polarized? Please guide
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Dear Meenakshi Kohli:
As you know, The polarization in which E field radiates energy in both the horizontal plane and vertical plane and in all the planes in between is known as circular polarization. In this polarization, electric field has two linear components which are perpendicular to each other with equal amplitude and 90 degree phase difference. The resulting E-field rotates in a circle around the direction of propagation. Based on direction of rotation there are two types viz. RHCP and LHCP. Circularly polarized light signal can be generated by passing linear polarized light signal through quarter wave plate (λ/4) at angle of 45 degree to the optical axis of plate.
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The advantages of Circular Polarization:
➨No polarization adjustment is required as it is fixed using OMT (Orthomode Transducer).
➨There is less chance of cross pol interference.
➨RFID reader does not have to be on the same plane and similar heights as RFID tags unlike linear polarization RFID reader.
➨RFID reader does not require to know the tag orientation unlike linear polarized RFID reader. Hence it is used for applications where one does not know the orientation of RFID tags while reading the data.
disadvantages of Circular Polarization
##########****
disadvantages of Circular Polarization:
➨It makes cost of antenna system higher.
➨It offers slightly lower cross pol isolation.
➨It offers shorter read range for RFID reader
You can benefit from this valuable article about your topic:
"Linear to left- and right-hand circular polarization conversion by using a metasurface structure"
Abstract:
By using a metasurface (MS) structure, a linearly polarized wave is converted to circularly polarized waves. Both right- and left-handed circular polarizations (RHCPs and LHCP) are obtained by a simple configuration in the proposed structure which consists of 16 unit cells arranged in a 4 × 4 layout. Each unit cell contains five horizontal and parallel strips embedded in a rectangular frame in which a single diagonal strip is placed from one corner to the opposed one. It is shown that the orientation of the diagonal line determines the handedness of the converted signal to be either LHCP or RHCP. In order to show the working conditions of the MS structure, scattering parameters are found for both co-polarized and cross-polarized responses. Axial ratio, an indicator for polarization conversion, is then obtained by dividing cross-polar response to co-polar response to demonstrate the transformation. The structure works for horizontally and vertically polarized linear waves in a wide band frequency range which is approximately 510 MHz. Since the suggested MS model is composed of a simple geometry for polarization conversion, it can be easily adjusted in any desired frequency bands for a variety of applications from the defence industry to medical, education, or communication areas.
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Also you can take a look at:
"Linear and circular-polarization conversion in X-band using anisotropic metasurface"
I hope it will be helpful...
Best wishes....
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Dear Researchers, hopefully someone can help me here:
I built a 2D model in COMSOL, of a simple three-layer covered conductor, surrounded by air.
This cable is for aerial power lines ,
Now, I need to compute the "Dielectric Strenght", this property is given in (V/m) or (kV/mm), of the most outer layer of the Cable.
Does anyone know how to do this in COMSOL ?
Best Regards !
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Yes, I would like to receive this code. Thanks very much for your general sharing.
Please send to this following email: zhaoliang0526@163.com. Thanks.
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I am trying to design a PIN Diode switch for a WR90 Rectangular waveguide ( X - Band) using HFSS software. I have learnt from some discussion that PIN Diode can be modelled using sheets and boundaries but how exactly that model i can use inside a waveguide as a switch? what are the parameters or extra devices i need to add? I couldn't find any open publications on PIN Diode switch in x-band rectangular waveguide Can someone recommend me some books or publications or blogs for better understanding of PIN Diode simulation in HFSS inside a waveguide.
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Hello,
Few papers are attached for your help.
Thanks,
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Dear Researchers :
Hope someone can help me to understand this :
In the Power Energy Industry, most o the insulators and Accesories/Elements in contact with the Electric Power Lines are made of Dielectric Materials such as Polyethylene, or Silicon Rubber (an Elastometer).
But all these materials should to be able to withstand Electrical Breakdown phenomena, like Partial Discharges in the interior of the Material, Electrical Treeing and Electrical Tracking.
Aiming for this, it is required, in the technical literature, and from Manufacturers' standards, to use Materials with low Dielectric Constant (Relative Permittivity)
But, What is the relationship between the Dielectric Constant and the phenomenon of Electrical Breakdown in a Dielectric Medium ?
How should I understand this ?
Best Regards to all !
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During alternation voltage source, dielectric material lead losses due to polarization, so we use minimum dielectric material constant for insulators.
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Other than LATEX, is there any tool/software to write a technical book where we can add figures and write equations
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Best tools you may try
1. Microsoft word
2. LATEX
3. Scrivener
4. Freedom
5. Google docs (online)
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I am looking to estimate or quantify the force exerted upon a piece of ferromagnetic material by a magnet or electromagnet through a couple of walls made from different material each.
My understanding is that the force "felt" by the ferromagnetic material will decay the farther away it is from the magnet and also due to the different material the walls are made of.
Currently my target would be to find an array of variables that can create a radial force of about 10 N the pushes the ferromagnetic towards the magnets.
I attached a picture to better explain.
I appreciate any response that might help calculate this.
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According to your pictures, you are talking about very short cylinders, and in this case, I guess it is not required that the strength of the force is independent of the z component of the position (if z is incident with the axis of the cylinder).
If you place a ferromagnetic ring coaxially inside the left configuration it will indeed experience a radial force toward the magnet. The total force on the ferromagnetic ring will be zero, of course, but if it were made from an elastomer filled with ferromagnetic particles, its diameter could increase under the influence of the magnet.
I'm not sure yet about the right configuration.
Please find an article dealing with shielding of static magnetic fields here:
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HFSS and Maxwell were made by Ansoft in the last century, and there actually were little problems with them. You could always trust the simulation provided by those systems.
However after Ansoft was absorbed by ANSYS, nothing was improved in solvers from engineering point of view. Instead some crazy non-scientific poorly documented things were introduced, probably programmed by game and CGI designers without any thoughts of engineering application.
One of the craziest thing I discovered lately is ANSYS's "closest point interpolation".
What is the "closest point" value, you may guess? Well, I think it is obvious - a value of the point found closest to the coordinate of interest.
It would be a very good approach feeding the discrete precalculated input fields, or material parameters for precisely simulating complex designs.
However what does ANSYS think about the closest point values!? You may be surprised.
Below, I show you a test of the clp() function, which SHOULD find a value of the closest point from the dataset "$dataset" for every mesh node with coordinates XYZ.
It should be placed in the material editor, in any property cell as clp($dataset, X,Y,Z).
According to manual, X,Y,Z, are provided in SI units, i.e. in meters. The output should be in the dataset units, but it is not, recognized by HFSS on practice. So I recommend making it unitless, and multiply by the desired unit, like clp(...)*1cel.
Now I define a simple dataset with a script:
<code>
dim pushdata()
redim pushdata(1) 'generate the data incrementally in dynamic dataset
pushdata(0)="NAME:Coordinates"
pushdata(1)=Array("NAME:DimUnits", "", "", "", "") 'in meters
for x = -1.1 to 1.1 step .1 'in millimeters
  for y=-1.1 to 1.1 step 0.1
    for z=-1.1 to 1.1 step 0.1
      redim preserve pushdata(ubound(pushdata)+1)
      pushdata(ubound(pushdata))=Array("NAME:Point", CDbl(x/1000), CDbl(y/1000), CDbl(z/1000), 1) ' see that "1" in the end. it is a value of "1" inside the Unit-BOX
      if ((abs(y)>=1) or (abs(x)>=1) or (abs(z)>=1)) then
        pushdata(ubound(pushdata))=Array("NAME:Point", CDbl(x/1000), CDbl(y/1000), CDbl(z/1000), 0) ' see that "0" in the end. it is a value of "0" AROUND the Unit-BOX
      end if
    next
  next
next
oProject.EditDataset "$Dataset", Array("NAME:$Dataset", pushdata) 'write the dataset to HFSS (ANSYS EDT))
</code>
Now lets see what the clp() function reads out from the dataset, and substitutes to material properties:
See the yellow and red lines on the plot below.
Obviously, those are NOT ones(1), and NOT zeroes(0), as one would expect.
I do not know what is that, but it is not a simple bug. I checked it in ANSYS EDT 2021 R1, and R2, both. It is a way how the programmer's head works.
Crazy stuff.
And we are forced to pay hundreds of thousands (some organizations pay millions) of Dollars for that, risking the corporate security btw. Because EDT is a security hole requiring Internet connection to work, and providing a backdoor for ANSYS, and anyone who could exploit that, to your system.
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Dear sir:
Thank you for sharing this important and valuable information .....
With best wishes....
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There is a complicated badly documented object structure in ANSYS EDT (HFSS, Maxwell). It allows many things with scripting, when you know how to access them. But it is a problem, since you usually do not know if the secret knowledge was not passed to you...
So, does anyone know how to get a value of a material property?
Like reading a value of dielectric constant, or an array of BH curve data?
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BTW, I did not know that direct notation with quotes works!
I usually use the global (project) notation with "$" prefix. Like $eps without quotes. It was required in older versions to use global $parameters in the material editor.
Do you specify your "eps" on the design level?
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Dear Researchers :
If someone is proficient in COMSOL and knows about the physics and applications of Electric Power Cables
Can help me on solving this model? What am I doing wrong ?
I need to compute the Temperature Distribution of this 2D model of a MV (35 kV) Power Cable.
The configuration is simple, and the application if for 25 kV AC.
I used a Study in two Steps
Step 1: a Frecuency Domain Analysis to solve first the Electric Currents (ec) and the Magnetic Fields (mf) physics. Followed from a
Step 2: a Stationary Study to solve the Heat Transfer phenomenon and its coupling with the (ec).
I'm attaching this image to shown how I can't get a Temperature Gradient, the Gradient I am getting is so tiny that practically the Temperature is uniform across all the Cable.
I'm doing something wrong
I'll appreciate the help,
Best Regards !
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Dear Franklin:
I agree with the opinions of my colleagues mentioned above, that it's difficult to find the problem since we can't see all the settings.
But you could benefit from this valuable article about your topic:
"Heat Transfer Modeling of Power Cables in Tunnels"
Electric power, in cities or for power plant outflow, is most often transmitted through underground cables. Due to increased electricity demands power suppliers make large investments to house these cables in deep or shallow tunnels.
The thermal environment is complex, with different kind of cables placed in different configurations, transmitting different powers. These are hard to take into account theorically, so thermal simulations using COMSOL Multiphysics® software were undertaken to measure the inaccuracy of the empirical models.
The Conjugate Heat Transfer interface is used, 2D and 3D models were developed and showed that several hypotheses lead to underestimation of the hottest cable temperature and two interesting possibility for improvement were found: the heat transfer correlations and cables proximity effects.
I have attached the pdf files ....
I hope it will be helpful...
With my best regards ...
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How can one simulate/produce two-port S-parameters between an antenna and an ideal isotropic antenna?
This should include phase shift due to the distance between antennas.
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Yes, that's essentially what both Malcolm White and I were saying initially. In the far field, the magnitude of the S21 is just given by the Friis transmission equation where the gain of the isotropic radiator/receiver is set to 1.
Now, on the phase, I see that you responded to Malcolm about the same time I was replying initially and since it posted above mine, I hadn't seen that in later posts. You're generally on the right track. Essentially, again in the far field, you can use e^(-ikd) to produce the radial phase shift. The question is what the angular phase behavior looks like, and as you indicate, includes both polarization as well as position. In the far field, there's no radial (longitudinal) component of the field, so if we put Z along the direction of propagation, that just leaves you with the X and Y components at an isotropic field probe. So, we're back to needing two components, just as you allude to in your response to Malcolm.
So where do you get them? The answer is pretty simple. You need a vector antenna/radiation pattern for the antenna creating the field. Any complete spherical radiation pattern requires measurement of two orthogonal polarizations at each point. Often, we only think of the scalar components to get a total power/gain in each direction, but if we want to understand circular/elliptical polarization components, etc. or perform near-to-far-field conversion, it's necessary to keep the relative phase information for each component. Once you have that information, you can work out your far-field magnitude and phase for each of the two components by applying the appropriate distance correction.
This shouldn't be surprising if you consider that's essentially how the pattern was obtained to begin with. Whether through direct far-field measurement or near-to-far-field conversion, the pattern is determined by measuring two orthogonal polarizations at a fixed distance from the antenna under test (AUT) creating a spherical surface around the AUT. From that, we know the magnitude and phase of two orthogonal polarizations on that surface and can calculate the magnitude and phase for any other spherical surface (or other arbitrary surface if we wanted) around the AUT. After all, that's what near-to-far-field conversion does. It's just more complicated since the field structure changes between near and far fields, while far-to-far-field can just be determined (or at least estimated) by the radial change.
Hope that helps.
Michael
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I have only come across V-antennas whose both the arms have equal (same) arm length. Is it possible to design to a V-antenna having unequal (dissimilar) arm lengths? If yes, then what would be the mathematical equation relating the arm lengths, wavelength and included angle?
Edit: Including the equations used in designing V-antenna having equal arm lengths. Is it possible to use these equations if the arm lengths are dissimilar (unequal)? If yes, what modifications do these equations require?
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The “Electromagnetic Radiation Energy and Planck’ Constant” suggested the existence of this constant, what do you think about it?
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For every metal (or material) used for coil (or other devices) in production of em waves, there should be a minimum required voltage vr for production of em waves.
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I am simulating helix antenna in hfss, right now, giving excitation with 50 ohms port. When I see the results of Z parameter (real). It shows lower than 50 ohms. Do not understand, if it can be true or I am making any mistake. Please advise.
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The impedance of an antenna can be anything from a few ohms to very high. A properly designed antenna will match to the impedance of the driving source for optimum power transfer. The 50 ohm value of the port is arbitrary and can be set to any value desired. Cable impedances come in many different values, such as 50, 75 and 300 ohms. Sometimes a low value antenna impedance is desired such as 10 ohms when connected to a low impedance solid state circuit.
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Can I please ask for good articles/papers/ thesis on Flat Lens Antenna to study? Is it metamaterial or antenna having a metamaterial at the back?
I am looking at this:
Trying to understand what is this?
Thank you
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Hi,
You See Rotman Lens Antenna, it's the same exemple,
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Hi,
We find a specific distribution of electric fields in structure for different frequencies which can be seen using em solvers and known as modes.
I would like to know how we can choose the required application depending on this specific spatial distribution.
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Hello,
few papers are attached....kindly go through and clear the doubts.
Thanks,
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I have a design with 2 dipoles working at different frequencies joined in one system and separated by Ferrite. I think, Ferrite was used to minimize the interference between 2 antennas as much as possible. I need to simulate this design in HFSS. Can I simulate ferrite in hfss or do I need to take permeability, permittivity numbers from the manufacturer (which are not available with the manufacturer).
All ferrites should be similar,,,right? does it matter different companies sell different ferrites with different permeability and permittivity?
Please advise so that I can see if I am thinking correct or not.
Thanks
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Hello,
you can refer these papers for simulation in HFSS.
Thanks,
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Should I make 2 antennas, one for 2.4 GHz and one for 5.8 GHz? How should I approach the problem if I want to design the antennas which cover 400 and 900 MHz and 2.4 and 5.8 GHz? All together in one unit and circularly polarized.
Please advise
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Did you mean helical antennas? I think 400 MHz to 900 MHz is a very wide band for a helical antenna.
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So, I have a design, two dipoles working at UHF and VHF. We fed using a diplexer. I am having difficulties with the testing using network analyzer. VHF passes but UHF, specially at 400 MHZ, the VSWR shoots to 2. 1 or even 2.3.
Is there anything I am missing and replace to pass vswr for UHF too?
Thank you
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You have to investigate and improve the matching between the source impedance and the input of the UHF port. You can measure S11 and see whether the resonance center frequency is lies at the minimum of S11. The minimum must at least lower than S11= -10dBs. May be you need to fine tune the path to the UHF antenna. Also, the radiation resistance may be smaller much deviated from the source resistance.
Best wishes
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So, I came across, where antennas are being tested in a building ( a plant), where all sorts of big equipment are around and of course the ceiling. lot of multipath which can affect the performance of an antenna. What is the cheapest way if I can get any suggestions to test the antennas, if we do not want to go outside and does not have a budget for a big anechoic chamber? Any suggestions are going for helpful.
Thanks
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Meenakshi Kohli you can use a plane wave test source in a room with the EM wave pointing towards the window side (open wall). Use low power at the test source. Keep the AUT in between the test source and window at far-field distance. This should work for small antennas whose dimensions are small compared to window opening. If the window can be opened, you can open it for tests.
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Helical antenna usually have fixed spacing between the coils. What is the advantage of varying the spacing between the helical antennas? Varying the pitch angle.
Thank you for your guidance in advance.
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In Helical Antenna:
The spacing and pitch Angle both very very important design parameters which decides the Directive Gain, HPBW and BWFN.
Advantages of varying Spacing (S):
1. The Directivity Gain of the helix is directly proportional to spacing (S) between the helical turns.
Hence, Higher directivity can be achieved by increasing the spacing (S) between the helical turns results.
2. HPBW and BWFN are inversely proportional to square root of spacing (S) between the helical turns.
Hence, sharp major lobe (either in broadside plane or Along the axis of helix) results for higher values of turn-spacing (S).
Advantages of Pitch Angle (Alpha):
Pitch Angle (alpha) and spacing (S) between the helical turns are directly proportional:
Spacing: S= C tan (alpha);
Where C is Circumference of Helix and
alpha= Pitch Angle.
tan (alpha) value increases with increase in alpha value.
Hence, increase in pitch angle (alpha), results in increase in spacing (S) between the helical turns and it will results in following advantages.
1. Higher directive gain
2. Sharp major lobe having less value of HPBW and BWFN.
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So, I have a helix antenna designed for 400 to 900 MHz. This antenna is designed using fabric and as a fabric, it gets wavy and scrambled which changes the performance of the helix. I am thinking of sewing a stabilizer (a thick fabric), which embroiders use so that the fabric can be stabilized as much as possible. But, I need suggestions on this idea as I do not know if I am making antenna LOSSY after sewing a stabilizer behind the fabric. I am attaching the stabilizer picture
Please advise.
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Good question
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Reading about helical antenna before begin to design. How many turns should a helix have? How can I determine good number of turns? I know Length of the antenna = NS. Should I just play with the pitch angle and spacing between the turns?
Appreciate your guidance.
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Length of the Helical antenna gives its Axial Length, A= NS. Axial Length A=NS, value also gives the modes of operation.
The value of length of helix, NS can be selected based on the following conditions
1. A=NS must be much smaller than wavelength, Lamda of helical antenna. It gives maximum radiation along the axis of helix. (End-fire radiation)
2. Directivity is directly proportional to the axial length NS. for higher directivity number of turns in helix must be more.
Directivity, D= {(15NSC^2)/(lambda)^3}
3. Axial ratio (AR)= {1+(1/2N)}, Number of turns must be more to reduce axial ration.
4. HPBW and BWFN are inversely proportional to square root of axial length. Therefore for unidirectional radiation NS value must be more.
In general if number of turns is more then it gives high directivity and almost unidectional radiation.
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Which types of electromobility or alternative solutions for the environmentally-friendly supply of motor vehicles are being developed in your countries?
Are they based mainly on purely electrical or hybrid engines that connect electric power with petrol or other, or power based on the combustion of hydrogen with oxygen?
Please reply
I invite you to the discussion
Thank you very much
Best wishes
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Comparative study on Japan n Korea... In recent years, the development and market participation of major makers of next-generation eco-green vehicles has been accelerating. Consumer interest has also increased. Consumer characteristics, consumption type, characteristics of next-generation eco-friendly vehicles, and government policies on next eco-green vehicles. In Korea, there was no significant difference by gender, age, monthly average income, and consumer type. However, there was no significant difference in purchase intention by gender, age, and monthly income, Respectively. In the case of Japan, there was no significant difference by gender, age, monthly income, and consumer type. In Korea, on the other hand, images such as brand, color, and design have positive effects on eco-friendly vehicles. In the case of Japan, image and stability have a positive effect on consumers' purchasing behavior. Therefore, it is important for Japanese consumers to consider not only the image of purchasing an eco-friendly vehicles, but also the safety of the vehicles body, appear. In the case of Korea, the socio-environmental value-seeking type has a significant relationship with the purchasing intention. In the case of socio-environmental value-seeking type, the government's support policy such as carbon dioxide tax, direct support from the national or local governments, gasoline tax, Carbon tax and fuel related tax relief showed positive effects. In the case of Japan, the price-seeking type and the socio-environmental value-seeking type were found to have a significant relationship with the purchasing intention. Both the price-seeking type and the socio-environmental value-seeking type showed that the carbon dioxide tax, Direct support, gasoline tax, gasoline tax, and carbon tax, etc. have positive effects... Yim, K. H., & Chong, M. Y. (2017). A Study on the Influence of Consumer Type on the Choice of Next-Generation Eco-Friendly Vehicle and Consumer Purchase Intention-Comparative Study on Japan and Korea. Journal of digital convergence, 15(11), 133-146.
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So, I need to design an impedance transformer from 50 to 250 ohms. Should I design a 50 ohm power splitter and then design a transformer from 50 to 250 ohms? Because, in power splitter, I am going from 50 to 70 and then again 50 ohms as the result of splitter. Getting confused, why I am going from 50 to 70 and then 50 and again go from 50 to 250? Is there any trade off I can do?
Please advise.
Thank you
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You do not seem to understand microwave components at all. You need to be very careful, or else things will not do what you expect them to. You need to read about microwave components.
A transformer that uses a 70 ohm section I expect is a quarter wave transformer which will match 100 ohms at one end to 50 ohms at the other. The splitter sees two lines going away from it in parallel. For the 50 ohm line to be matched the two lines need to be 100 ohms each so that in parallel they are 50 ohms.
A 70 ohm line quarter wave long is a standard inverting transformer which looks like 100 ohms at one end if there is 50 ohms at the other, so if it has a 50 ohm line going out it presents the 100 ohms at the other end that the single input line needs at the split.
To get from one 50 ohm line to a 250 ohm line you need a quarter wave long line of impedance square root of 12500 ohms, which is close to 111 ohms.
The lines are almost never exactly a quarter wave long because the steps in size look like capacitors which have a similar effect to extra line length, so the line lengths are usually shorter.
If the transformer doesn't work at the frequency you want, find out which frequency it does work at, then if that frequency is too high or low, make the quarter wave section longer or shorter by the ratio of the two frequencies, which will get you very close.
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Microstrip width does matter in impedance but does the thickness of metal also affect the impedance?
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The thickness of the metal has a much smaller effect than the width of the metal and the thickness of the dielectric, but it does have some effect. The empirical formulae for impedance use width, and an effective width can be used in these formulae. The effective width is calculated by a simple formula that includes the thickness.
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Is there any matematerial which can reflect right handed circular polarization into Left handed circular polarization or vice versa of the EM waves operating in ultra-wide band?
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Any good conductor, e.g. a metal surface, reverses the direction of circular polarization on reflection, for all frequencies for which it is a good conductor.
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I am following the below method so far & need guidance to further modify it:
1) Making a specimen
2) Making an Electromagnet using prepared specimen
3) Using DC & AC Source to find BH- Curve
4) Calculate Permeability from graph by taking respective points
Please make your suggestions regarding all 4 points
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It all depends on the parameters...what are you REALLY interested in..the field vs current ar one point..the field homogeneity..saturation properties etc etc..you may find a lot of hint in the IMMW proceedings (Intl magnet measurement workshops)and Also on the JACOW pages as well as in the CERN library ...CDS CERN..(all public access with free downloads.In addition you may look into the CERN accelerator school proceedings for magnetic measurements (via CDS CERN)
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Hi there
what is the formula of magnetic field force applying on Ferromagnetic material?
can we use the formula of magnetic field applying on magnetic dipoles force to calculate the magnetic field force applying on Ferromagnetic material?
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I wasn't sure how to insert Greek characters in RG answers, so my0 stands for the permeability of vacuum = 4 * pi * 10^-7.
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I designed planar circular monopole antenna . Its gain is 3.89 dBi and realized gain is also 3.89 dBi. Should there be difference of 10 dB in the values of Gain and Realized gain? Please guide
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From the CST help page
Some Farfield Terms
Directivity: The directivity of an antenna is defined as "the ratio of the radiation intensity in a given direction from the antenna to the radiation intensity averaged over all directions." The radiation intensity is given by the total power radiated by the antenna divided by 4p:
📷
Gain: Accordingly, the gain is defined similarly but is related to the input or accepted power of the structure. In the case of a loss-free antenna (no conductional or dielectric losses), the gain is equal to the directivity. Note, that power flowing out any port is not considered as accepted by the structure.
📷
Realized Gain: The realized gain is defined by gain * (1 - Balance^2), it includes the impedance mismatch loss.
E-field pattern: The electric-field pattern provides a distance-independent characterization of the radiation pattern. It is directly related to the electric field evaluated using the farfield approximation:
📷
Due to its definition, the E-field pattern has the unit of a voltage.
Radiation efficiency: The antenna radiation efficiency is defined as the ratio of gain to directivity or equally the ratio between the radiated to accepted (input) power of the antenna:
📷 or 📷
Total efficiency: The total efficiency is defined as the ratio of radiated to stimulated power of the antenna:
📷
Compared to the input power, the stimulated power considers any occurring reflections at the feeding location.
Reflection efficiency: The reflection efficiency is defined as the ratio of input to stimulated power. Note that the input power is the accepted power, i.e. reflected power and power flowing out any port of the simulated structure are not included.
📷
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I have designed a metasurface which has a thickness of 0.78mm. Its operating frequency is around 15 GHz. Can I call it ultra thin?. In terms of lamda, the thickness of metasurface is lamda/23
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See? for example, A.A.Kirilenko and A.O.Perov, “On the
common nature of the enhanced and resonance transmission through the periodical set of holes,” IEEE Trans. Antennas Propag., vol. 56, no. 10, pp. 3210–3216, Oct. 2008. + references
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The symbol for meters is an m; but so it is for mili (10e-3). Is there any way to differentiate between the two, like using italics?
Thank you.
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ISU general symbols for universal dictionary
m for meter....
10e-3 for mili.....
The International System of Units consists of a set of base units, derived units, and a set of decimal-based multipliers that are used as prefixes.
I am agree in a totality with Jonathan Magnes statement he quoted in his answer of this question.
Ashish
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Whenever a PCB layout is subject to noise (such as being in the vicinity of switching mode power supplies or high dv/dt and di/dt incidents), is it better to route the critical signal traces (such as gating signals) wider or narrower? (I understand that using planes is a good solution, wherever possible. But many times we have to use traces.) Which one has the advantage in terms of being more immune to the noise?
Thanks!
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Adding to the colleague above, I would propose to shield the critical parts of the circuit against the interference by near or far electromagnetic radiation sources. This can be accomplished by using ground planes.
Te other solution may be to use balanced wire system such that the common mode signal will be cancelled.
The last precaution is to reduce the impedance level in the circuit such that any induced voltage will induce little or negligible current.
Best wishes
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Dear researchers and friends, please tell me the formula for calculating Reflection loss in EMI SE? I used 20 log [S11], is it correct?
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Thanks Rafia Raees.
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Hello all,
I am trying to measure "Noise Figure (NF)" value of the LNA (IC of MAX2678) by using VNA (without Noise Source, and with perfect 50-ohm test systems) and I am following the steps in given "Vector Network Analyzer Application Note " as attached in the following link or in the attachment:
However, even though I am adjusting the LNA input power so that LNA does not enter compression (saturation) and besides, I am calibrating my VNA in the frequency range that meets with my LNA's operating frequency range, in the end, I am observing "negative Noise Figure" from the LNA measurements.
In theory, it is impossible to see negative NF. So; is there anyone who has experienced such a situation before? Or why I am observing "negative noise figure " from my LNA measurement with VNA (without Noise source)?
Best regards,
Thank you in advance.
Huriye.
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You are using the so called cold noise measurement technique. This type of measurement using measured s parameter data and noise power values obtained from source pulling about a reflection coefficient with a Gamma of 0.5 or so. Be certain that the device is stable and check to see if the s data returned during measurement makes sense. Is the device matched? As a sanity check that your cal is good, measure a simple item prior to your LNA DUT. A 3 db pad should return ~ a 3 dB NF.
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Greetings...
Is there a "general" solution to the telegrapher's equation {voltage or current on a transmission line}?
I mean by "general": without ignore of losses and without assuming sinusoidal excitation.
Kindly refer to some references on that topic.
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Hey Friends,
I am working on microstrip antennas and I have stuck at a point where I have to give the feed to the radiating patch. I am working on equilateral patch antennas and I know how to give the coaxial probe but not about of what dimensions should I use. What will be diameter of coaxial probe as I am not aware how to calculate the impedance of an equilateral patch?
So basically I have two doubts.
1. First one is how to calculate the impedance of an equilateral patch antenna and
2. How to calculate the dimensions or diameter of coaxial feed as per impedance of the equilateral antenna?
I am working on HFSS. Kindly provide any technical paper or calculations on them. Thanks in advance.
Regards
Munish Kumar
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i am working on mmwave patch antenna design....what should be the outer and inner diameter of a coaxial cable feed??
I have found for my frequencies 1.85mm and 2.92mm k type connectors are suitable...Is that good one...
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In CST , i am placing a dielectric material between two antennas and measuring their s11 and s21. I tried Nicolson-Ross-Weir Method but it is not giving me correct dielectric constant value. Basically i am just trying to calculate FR-4 and Rogers substrates dielectric using antennas.I am calculating for the freq span of 2-6 GHz Antenna Setup is in following picture
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Hello,
To measure parameters like permittivity and permeability, it is the transmission lines that is used in transmission and/or in reflection mode. for better understanding of this type of measurement, you can read this application note.
Thanks,
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Can a high AC (~10 KV) Discharge can effect nearby (~10 mm) DC device?
What will be its effect?
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The effect depends strongly on the AC frequence.
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Bioresonance is a non-invasive therapy which involves placing electrodes on your skin for diagnosis and treatment. The electrodes are connected to a Bicom machine which checks the energy wavelengths coming from your body, and then counteracts bad frequencies by restoring the optimum balance.
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I would like to remind my distinguished colleagues that ResearchGate is about scientific research based on the scientific method. Therefore, I believe that RG is not a good place to discuss usefulness of pseudoscientific devices like "Quantum health scanner". Apparently, the use of similar devices has been banned in the US.
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Some of the books have always been used as a standard reference in that particular field. I am looking for such book on active components design theory and analysis; and that could have system level implementation/examples/models.
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Hello,
Practical Rf Circuit Design for Modern Wireless Systems, Volume II: Active Circuits ( by Rowan Gilmore (Author), Les Besser (Contributor) )
An Introduction To RF Circuit Design For Communication Systems 1st Edition
( Roger C. Palmer (Author) )
Thanks
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Is it possible to break a π bond between a solute and a magnetic solvent using magnetic force?
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yes, i think it is possible.
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Is it possible to break a π bond between a solute and a magnetic solvent using magnetic force?
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I believe yes, Amir hossein Aref it depends on what/which molecule you are considering. As for example if we consider weaker bonded CH3CL, in which C-Cl specifically. Then we can calculate the energy require to break this bond. Like for 9 debye the breaking energy lies near about 3.5eV.
So theoretically you can break these like weaker bonds using electric/magnetic force, And if you can build a machine which such capabilities you can also practically break these type of bonds.
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What is the main difference between dual band and dual radio?
Let
A system equipped with:
Dual Band= 2.4 GHz and 5 GHz
Dual Radio=802.11 and 802.14.5
where 802.11 with 5GHz is deploy between air to air link
and 802.11 with 2.4 GHz between air to ground.
similarly some nodes are also connected through 802.15.4 with 2.4 GHz between air to air.
The above system is dual band dual radio
or triple band dual radio
or triple band triple radio?
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Dual band refers to a device which uses two different frequencies to communicate.
Dual radio refers to a device which uses two different protocols to communicate.
Maybe an illustration would help. A dual band device is like a person at a party who can move between two different rooms (different frequencies) to talk with other people, while a single band device would be limited to talking to people in only one room. On the other hand, a dual radio device can speak with people who speak in two different languages, while a single radio device can only speak one language.
A dual radio device is typically used as an intermediary between two different networks like 802.11 (like WiFi) and 802.15.4 (like many wireless sensors).
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Hi,
I have noticed that FSS unit cell tested inside a waveguide shows a wider bandwidth than a periodic surface of the same unit cell (with exact same cell dimensions) tested in free space.
Apart from the difference in the wave impedance, what could possibly make waveguide have wider S-parameters response?
Thanks..
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Dear Baraa,
Thank you for sharing the details of your FSS design with us. I assume that the parameters of your periodic FSS structure are those of a square or rectangular lattice? From what I remember about FSS measurements in rectangular waveguide simulators, the lattice of your perodic structure must be at least rectangular in form and you need to place two unit cells side-by-side across the broad dimension of the waveguide. This is to emulate the correct symmetry and periodic boundary conditions of the full lattice. Did you use side-by-side elements in your waveguide simulations and measurements, or just one element? You can think of this two-element arrangement as generating an infinite set of image elements with respect to the side walls of the waveguide. You would be not able to simulate a triangular lattice in a rectangular waveguide, for example. Whilst I would fully expect your computed and measured results to agree well for whatever FSS element you place in the waveguide, the trick in an FSS waveguide measurement is to mimic the actual periodic boundary conditions that occur in a full lattice. If you've only modelled and measured a single FSS element in the waveguide, the results would not pertain to the same lattice parameters of a fully periodic (free-space) structure involving that element. My previous comments about the plane-wave decomposition and frequency-dependent angle of incidence in the waveguide measurement would still apply to the case of two side-by-side elements placed in the waveguide.
Regards,
Ray
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Dear Colleagues and Professors,
I am doing experiments on the interaction between magnetic liquid and strong magnets to display the magnetic field line of a magnet. In best conditions, the magnetic lines will be showned on the surface of the liquid in the form of spines as in this video:
The components of my experiment include:
1.The Neodymium rare earth magnet with strong magnetic field strength (Figure 1).
2.Magnetic liquid is a mixture of vegetable oil and laser ink toner (content of oil and toner changes with different ratios) (Figure 2).
I have changed ratios of the content in the magnetic liquid mixture as well as used the very strong magnets but can not do the effect as above (figure 0).
I attach some of my results. Fig 2 shows magnetic liquid mixture in my experiment. Fig 3 shows interaction between the magnetic liquid mixture and magnet. Fig 4 shows interaction between the magnetic liquid mixture and magnet with adding vegetable oil.
Please give me advise. I hope to hear from you and sincerely thank Colleagues and Professors.
Best regards.
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Thank you very much for your help, Dr. Søren Kyale
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Dear colleagues,
We are conducting experiments on battery-magnet systems running in copper tube (also known as World's Simplest Electric Train). Our equipments includes:
-A pin size AAA or AA buy from duracell or engyzer company, voltage 1.5 V.
-Two Neodymium magnets are larger than batteries.
- An uncoated copper coil, 54 rounds / 1.5 dm, larger diameter than the battery, straight.
Attach two magnets to both ends of the battery and push it into the copper tube. The copper tube vibrates but the battery moves only a few millimeters and stops.
I hope the experts help me to make the battery move in the coil like video:
I look forward to hearing from you soon.
Thank you very much.
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Two points:
- The inner diameter of the coil has to be larger than the outer diameter of the magnets in order to let the battery-magnets-assembly move freely.
- The polarizations of the magnets have to be directed in opposite directions.
If you would just like to amaze your students by a simple setup which produces (rotary) movement you can avoid the tedious task of winding a long coil: Just take an AA-battery, one magnet, a short chipboard screw (made from steel) and a short piece of flex wire. Put the magnet on the head of the screw, connect the upward pointing tip of the screw to the negative pol at the bottom of the vertical battery. Due to the magnet, the screw and the magnet will hang from the bottom of the battery. Connect the wire to the positive battery pole, and touch the side of the magnet with the other end of the wire. Magnet and screw will start to rotate fast.
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Since there are long term treatments for some diseases or many type of cancers not knowing how to be treated, im wondering how brain activity can ever control the disease.
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Positivity (positive attitude) leads to the hope of improving the disease and in my opinion it really accelerate the speed of recovery from a disease.
For curing cancer pranayam (breathing practices) and meditation are really beneficial.
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The skin depth provides an approximation for field penetration in a conductor and describes the induced eddy current density decays from the surface to the inside of the condutor.
However, if the conductor is very small or extremely thin, for instance the aluminum particle with 100um diameter, will there be eddy current in the aluminum particle? (the skin depth of aluminum in magnetic field with frequency 4KHz is around 1.3mm)
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Dear Yuze,
What has been by the colleagues is okay. It is so that alternating current will cause an alternating magnetic field in a plane normal to the flow of the original ac current. This alternating magnetic field will induce secondary alternating current which aids the current nearer the surface and opposes the primary current flowing in nearer the interior. It follow that the current will be nonhomogeneously distributed at the cross section of the conductor where the current is more concentrated at the surface region.
So, the skin effect is the consequence of the induced secondary eddy currents. This effect is always present irrespective of the thickness of the conductor. It is advisable not to make the conductor thicker than the skin depth to save materials of the conductors. However the skin effect is always present irrespective of the thickness of the conductor.
Best wishes
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I am trying to design a rectangular waveguide (WR12) power divider/combiner to split/combine my signal and at the same time maintain a good isolation between the two fan-out legs.
In my simulation, I have tried a simple T junction with a septum in the middle, it works well as a fan-out and combiner but the isolation is poor.
Does anyone know any design tricks so I can achieve a good isolation while maintaining a good power dividing insertion loss? I can't use isolator structure in my design since my signal will go both way.
Thanks!
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Hi Smrity,
Thank you very much for your answer and the paper. The SIW paper is very interesting! I could use it for a fanout design in one of our boards.
Best regards,
Wei
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if energy neither be created nor be destroyed, then from where current carrying solenoid got magnetic energy....if electric charge is fixed, how magnetism is created....
do electric charge is first or electric force is first (analogous to hen is first or its egg is first)?
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When electric charges are moving, stationary charges beside them feel a stronger force than if they are not moving. Stationary charges in front of and behind them feel a weaker force. This can be pictured as distortion of the lines of force by relativistic length contraction - some lines of force move from in front of and behind the charge to the sides. When electrons move and their associated positive charges don't then there is an imbalance in the forces from the two that we call magnetism.
Magnetism is only what electrostatics look like under relativity.
The charges don't change when thy are moving, the space and fields around them become distorted to us, creating imbalanced forces that we call magnetism.
In the solenoid, the electrons are moving, but the positively charged metal lattice doesn't move, so there is an imbalanced force from the two, in most directions.
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Please help me to resolve some doubts as below
1. All matter emits electromagnetic radiation when it has a temperature above absolute zero. Do they emit radiations below this? (Say -500K) if yes, how to calculate their emission if emissivity known.
(University Munich and the Max Planck Institute of Quantum Optics in Garching have now created an atomic gas in the lab that has nonetheless negative Kelvin values (Science, Jan 4, 2013).
2.using Weins law, we can calculate the peak wavelength. Example: Radiation from mammals and the living human body: Mammals at roughly 300 K emit in the far infrared.
Considering this example, if go on either heating or cooling any object (in the suitable controlled atmosphere) will it emit radiations other than thermal? Like, will it emit microwaves,radio waves or other side UV and x,gamma etc...
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People have achieved negative absolute temperatures but that is in nano kelvins by magnetic cooling. However the temperature we refer as zero kelvin is actually a little above absolute zero. So basically the negative temperatures we are talking about a temperature above absolute zero that will radiate for sure. But nobody knows what is the absolute zero but be sure it will be some fractions of kelvin below 0 K. I think getting a temperature even like -1 K is hypothetical.
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At present, what is the easiest way to measure temperature during RF heating?
I am monitoring the temperature in heating grains and pests using radio frequency energy. The frequency used is 27.12 MHz and the power can be adjusted from 0 to 15 Kilowatt.
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Given that graphene is IR transparent, yet highly conductive, it should provide a workable window for most any Faraday cage.
I just skimmed the article but I think this may work as a window too, unless the substate blocks IR...
I am not 100% on this. However, I believe it is worth some experimentation.
All Negative criticism greatly appreciated.
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How does magnetic field heat? Does it heat to dielectric materials?
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Time-varying magnetic fields may heat in 2 different ways:
  1. By inducing currents in materials with some conductivity. In this case, heating is effected via the resistive losses.
  2. By forcing magnetic dipoles to reorient according to the orientation of the magnetic field. In this case, heating is effected by the internal "friction" of the dipoles reorienting.
Regarding your setup (dielectric between capacitor's plates), I'd guess that the dielectric is shielded such that it won't be heated directly. But the plates might be heated (currents induced), resulting in indirect heating of the dielectric by conducted heat.
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American interest in 'gravity control propulsion research' intensified during the early 1950s. Literature from that period used the terms anti-gravity, anti-gravitation, barycentric, counterbary, electrogravitics (eGrav), G-projects, gravitics, gravity control, and gravity propulsion. Their publicized goals were to develop and discover technologies and theories for the manipulation of gravity or gravity-like fields for propulsion.
Although general relativity theory appeared to prohibit anti-gravity propulsion, several programs were funded to develop it through gravitation research from 1955 to 1974. The names of many contributors to general relativity and those of the golden age of general relativity have appeared among documents about the institutions that had served as the theoretical research components of those programs.
This question is intended to explore possibilities to control gravitation using an electromagnetic field.
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Yes, it was done using horizontal light beam. See the paper on the effect of light on gravitational forces by light.  Rancourt and Phil.  Tatersall. More experiments are being done this summer using blue laser light.
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Why the E plane beam width of monopole antenna gets narrow when we increase the width of ground plane of monopole antenna???
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Thanks so much Mr. Malcolm , Mr Rusan and MR Sudipta 
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when we design any millimeter wave antenna for e.g at 1-2mm, what type of connectors are used?
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Hi Akhilesh,
Well, it all depends on your operating frequency. SMA is no good above 26.5 GHz, generally. When you said 1-2mm, I assumed you meant that was the wavelength (in free space), corresponding to about 150-300 GHz. If, instead, you mean that the antenna is 1-2mm in size, perhaps half a wavelength or smaller if used on a high-dielectric constant substrate, then it could be below 100 GHz.
Up to 110 GHz, you have the option of using 1mm coax -- but I can tell you from experience that the connectors, adapters, and cal kits for measurement are EXTREMELY expensive, and frankly don't perform very well. (I had to test a part once in 1mm coax where the performance of the part was far better than that of the test adapters, making the test practically meaningless). I wouldn't recommend it.
Really, for anything above 50 GHz, I would use waveguide. Waveguide to printed-circuit launchers can be made, but are typically custom. If you're geometry just wouldn't support a waveguide housing, then the best I can suggest is to test your antenna on a wafer probe station. Mm-wave wafer probes are readily available, but depending on what you want to measure (beam pattern, etc.) the geometry could be awkward.
Matt
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I'm trying to model the inductance of a wire in the presence of an external magnetic field and would like any paper references or models that have been developed for this.  
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@ Joseph Kay
Your problem is not exactly "... wire in air ...". Your wire is affected by the position-dependent variations of the "magnetic path" of your motor. This comprises - aside from the path through rotor and stator - 2 air gaps. The whole setup is such that the permeability of the path varies with the position of the poles of rotor and stator versus each other. This effect is well-known from BLDC/EC motors and can be used to measure the rotor position.
In principle this setup can be calculated, though a lot of parameters are required and the calculations are non-trivial. If you can get access to some appropriate simulation software (COMSOL and alike) you might get an impression of the changes, geometries and alike. Otherwise you could measure the inductance - gradually (eg. 1 ° per step) rotating the rotor between individual measurements and plotting the results.
Regards
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FMR signal can only be identified significantly, if the hrf(Magnetic field component) of RF wave is orthogonal to the external magnetic field applied. Is it also necessary with EPR detection?