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So, it used to be under the 1D results. now in 2021 CST, I donot see it under 1D results. I have checked, Uner the POst-Processing tab, in the S-Parameter calculations; calculate Z parameter is checked. But, still I donot see Z parameter under the 1D results. Please advise, how to check real and imag Z in CST 2021?
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Cannot see it...
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Hello!
I am specifically looking for research topics related to the simulation of vehicular antenna integration for both 5.9 GHz V2X and mm-wave 5G vehicle to network communication. Could anyone please provide me with any direction?
Thanks in advance!
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Cellular V2X with MIMO and beamforming, could be an interesting topic.
That way you have you baseline C-V2X over which you see the impact of number of antennas by modeling MIMO and beamforming.
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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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The single polarization LPDA is comprised of two booms (solid->cylinder->aluminum). Placement of mono-poles on the booms are complementary, i.e., mono-poles are alternatively placed on the booms to constitute individual dipoles.
In HFSS, I was trying connect the face-center of the booms at the top through "Lumped Port" with a defined line. However, that is not quite working out. S11, S22, is terribly high (~ -1 dB). Radiation pattern and directivity (~ 2.5dB) , realized gain is also not as expected.
Therefore, I suspect that I may not have assigned excitation to my structure properly. In CST people assigns "Discrete Port". I would be obliged if someone could kindly share his/her invaluable expertise and suggestion on this.
Also, the "stub" at bottom of the dipole has not been connected to the booms. Since, when the "stub" (length ~ maximum wavelength/8) was connected (through "unite") with the booms in existing model (in the image) max-directivity was further degraded to ~1.6 dBi
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I think you have not defined your port correctly. It should be between the edges, and not go across faces. See https://www.youtube.com/watch?v=KkiCTtLegjQ
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I am in search of journals or peer reviewed conferences where I can submit my paper on antenna. The paper has section like simulation, fabrication and testing results. I know of IEEE OJAP and IEEE antenna and propagation letters. But if I can get suggestions for other journals or peer reviewed conference on antennas ?
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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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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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If we connect the top and ground metal layers with a lot of Via, will the parasitic capacitance increase or decrease? As far as I know, it will reduce resistance.
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Hi
Having too many Via in PCB can introduce significant parasitic capacitance. If it is known that the diameter of the solder mask on the ground layer of the via is D2, the diameter of the via pad is D1, the thickness of the PCB is T, and the dielectric constant of the PCB board substrate is ε, the parasitic capacitance of the via is approximately C=1.41εTD1/(D2-D1)
The main effect of the parasitic capacitance of the via hole on the circuit is to extend the rise time of the signal and reduce the speed of the circuit. In addition, the smaller the via, its own parasitic capacitance. The smaller, the more suitable for high-speed circuits.
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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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Hello to all
Two questions
1. Does the use of metals with high magnetic permeability, such as iron alloy in the waveguide, cause insertion losses?
2- What about chrome or copper plating?
If you know the article in this field, please introduce it. Thank you
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Please find the attached files.
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I am looking for papers/articles concentrated on UAS/drone wing antennas. Any directions are appreciated.
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Dear Meenakshi Kohli:
You can benefit from these valuable Links, and articles about your topic:
I hope it will be helpful...
Best wishes....
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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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Out of these 5 universities can you rate them from top to bottom which is best for coursework and research opportunities for Masters in Antenna Specialization.
Arizona State University, North Carolina State University, Virginia Tech, The Ohio State University, UT Dallas.
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Dear
You can benefit from this Link about your topic:
You can enter the name of any university that you want to know its rank in the search box.
I hope it will be helpful...
Best wishes...
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Hello .
I want to design and build a waveguide load in X Band.
1- How to design that the VSWR is maximum 1.1? (What should I use inside the waveguide, what material? With what dimensions?)
2-How to test it with Network Analyzer after making it?
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Buy a sheet of microwave absorber, cut a long triangle with a sharp point and glue it to one large wall of the waveguide with the point pointing towards where the power comes from, or glue two to both large walls. The longer the triangle and the sharper the point the better the match, generally. You can do it with stepped absorbers, or a pyramidal absorber too. It is hard to design to a vswr of 1.1 unless you design a stepped absorber and are very sure of its complex dielectric and magnetic constants, but making a taper longer will usually improve the vswr. The sharpness of the point is important. If it needs to cope with high power the sharpness of the point can be a problem because it may melt if the absorber has high absorption.
You could glue it to the side walls but it may need to be longer, depending whether the loss is magnetic or resistive.
You can also use a vane of nichrome on kapton film between slits on the centre-lines of the wide faces of the waveguide. If you do this you can adjust the way it tapers in while looking at the S11. https://www.dupont.com/products/kapton-rs.html might also be suitable.
You can test it on a Vector Network Analyser (VNA) with a good coax to waveguide adaptor. 1.1 vswr is about -26 dB so if you want to be reasonably accurate the adaptor needs to have S11 less than -40, unless you can calibrate on the waveguide side, using waveguide open short and load, for instance.
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Hello dear engineers.
I designed a coaxial adapter for X-band waveguides. Now I want help to test and tune with the network analyzer device. How should I test it? If you know a reference, please help Thanks
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Impedance of normal size waveguide is 300 ohms or more and varies with frequency. There are standard equations. See https://www.microwaves101.com/encyclopedias/waveguide-wave-impedance, but it is more complicated than this, so look at more references. There is (at least) one definition of impedance that depends on the height to width ratio, and one that doesn't. Even your smallest height waveguide will be more than 50 ohms. I don't think you will find a 50 ohm waveguide load. Your transition should look like 50 ohms from the coax end and like whatever impedance the waveguide is from the other end. If it has no or very small (-20dB?) reflection seen from the coax end, and small losses (it probably will have) then it will have a low reflection from the waveguide end too. Lossless components without ferrites in have th same match (S11=S22 S21=S12) from both directions.
answer to 3
If you put a horn with a gradual taper (and no step) on the end of the waveguide it will be a good load - it will radiate with low reflection. Also if you put a piece of absorber with a good point and a long taper in the guide, it will be a good load, if the taper is long enough. You can't get a good load by putting a different size waveguide on, there will be a reflection from the step in nearly every case. Reflection = bad load
I don't understand question 1
2 yes - with no step in the waveguide, or a taper between the two sizes, several wavelengths long.
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Hi everyone,
I have designed one mobile antenna. When is I was trying to calculate the SAR values for this antenna I got an error "the total mass (0 g) smaller than selected SAR averaging mass? Please select smaller average mass". Did anyone encounter this type of error while calculating SAR value? If yes please help me how I can get a SAR value.
Thank you
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I face the same issue and I have tried to reduce the volume didn't make difference. I don't know how to fix.
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Can anyone please tell me.. what should be the gain, bandwidth, radiation pattern, polarization for 5G antennas of different bands like sub 6 GHz, above or near 26 GHz.
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welcome!
The antennas required may be either multiband pr wideband antennas to cover the transmission on multiple bands of the 5G either in sub 6GHz bands or in mm wave bands.
More interest will directed to MIMO and massive MIMO antennas. Whish are antenna arrays in the mounted on the base stations.
Best wishes
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quadrature coupler supports wide bandwidth or not in antenna?
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I Don't think it will be able to support it.
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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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Can I connect 2 capacitors in series/parallel to get 180 deg phase shift,? only 2 capacitors?
I need to have total impedance of 200 ohms at 2.4 GHz.
please advise
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Both are different things :
1.phase shift between input and output across a device
2. phase shift between current and voltage across a device
Two capacitors in series can not provide phase shift of 180 between input and output. So, it depends upon the quantities in which you need phase shift. No, nowadays amplifiers are available in miniature form or IC form (maybe you can use that, comparable or even smaller than the size of conventional capacitors).
That's how I can help, may be some faculty or researcher from the concerned domain may provide a useful answer and suggestion to your query.
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Electronic steering should be possible while creating lower side lobes due to the possibility of a lambda/2 spacing.
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At first thank you a lot for the answers. I planned to build up an array of horn antennas because of the possibilities of electric steering (that´s why I mentioned side lobes before in the wrong relation I think), hence there might be a compromise in the selection of longer or more horns for the same gain (or maybe longer and mechanically steerable horns).
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Hi, We want to measure the radiation patterns of an implantable antenna. The mimicking gel that we are using has different conductivity than that used for simulations. We want to increase the conductivity of our mimicking gel without increasing the permittivity.
We know that adding sugar and salt will increase the conductivity. However, it decreases the permittivity!!!
Any suggestions?
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I don't have an answer, but a warning. In microwaves and RF it is the refractive index that matters. The real part determines the wavelength and the imaginary part the losses. The refractive index is the square root of the relative permittivity - ignoring permeability. When you take the square root of the complex relative permittivity, it halves the angle of the complex number as well as taking the square root of its length, and the imaginary term in the permittivity, which will be changed by changing the conductivity, will result in the real part of the refractive index being changed. If you want the real part of the refractive index to be unchanged, it may be necessary that the real part of the permittivity falls a bit if the conductivity increases. It is worth working out the numbers for the real and imaginary refractive index you want and what permittivity that results in.
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I have new results of an investigation of an antenna design based on the simulation in HFSS.
What are some journals that publish Antenna Simulation papers without experimental validation and theoretical part?
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Dear respected colleague Vadym Slyusar ,
It is clear that this journal has a first filter by the editor. It may be that the paper must be strengthen.
Dear Colleague,
You can read some papers published in Pear to find our the accepted level by them.
Sometimes we get paper rejection from them.
I can give you another journal to publish in it.http://www.jocm.us/
Journal of communications JCM
I am an editor in this journal. It is scopus.
I wish you success.
Abdelhalim
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By simulation of nanoantennas need to take into account a quantum capacity, a kinetic inductance, plasmons, a quantum conductivity, etc. What electromagnetics simulators allow you to do this (HFSS, CST, etc.)?
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COMSOL includes lots of solvers and also allows you to add you own equations to the mix.
For instance
I'm not sure if this example will be helpful or not.
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Do cellular phones which support LTE have Diversity/MIMO antennas in the 700 MHz bands in addition to the higher bands?
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I would like to pay your attention to the pdf found in the link:https://www-file.huawei.com/-/media/corporate/pdf/mbb/2020/4x4-mimo.pdf?la=en
They speak about user equipment having up to 4 antennas. We developed MIMO antennas for the mobile phone:
Best wishes
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Based on the information from the SpaceX Twitter account can be concluded that the Falcon9 and Starship will be used the Starlink communication antenna as well. What is your opinion about the type of this antenna? I think that it is a Phased antenna array or a digital antenna array. And you?
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Dear Vadym,
surely there is some paper or article about it, at least with conjectures. In any case I pass you this interesting video where he disembowels the antenna in a quite detailed way. I'm sure it will be of interest to you.
Best regards
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I have a dipole antenna working 230 - 400 MHz. I need 400-450 MHz covered. What should I do with the structure so that my frequency moves to higher?
Thank you
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as you well know the wavelength is inversely proportional to the frequency.
(lambda=c/f). So if you want a resonant dipole at higher frequencies, the size of the dipole should be smaller, proportionally to the formula described above.
In that case, making the dipole approximately 1.5 times shorter should give satisfactory results.
I hope that solved. If you have any other questions, do not hesitate to ask.
Best regards,
Miguell
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Am actually working on radio telescope antenna design. One of the constrain to be met is to achieve circular polarization. And for the application I am targeting, I will require to design a planar low profile antenna.
I came across meta-surface antenna where the designs were made to convert linearly polarized signals into a circularly polarized radiating antenna. Can you please tell me if this concept can be used as a receiving antenna, so that it can be used to receive faint radio signals in circular polarization using a linearly polarized antenna.
Thank you
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Yes, definitely same antenna can used for receiving the purpose, as the antenna reciprocal device. Hence as per reciprocity theorem: The receive and transmit properties of an antenna are identical. Hence, antennas do not have distinct transmit and receive radiation patterns - if you know the radiation pattern in the transmit mode then you also know the pattern in the receive mode.
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Hello everyone:
In HFSS I have designed two Dipole Antenna with 50cm distance between them. When I change the size of the Radiation Box S-parameter results (S11 and S21) are affected. I increased the pass number and initial mesh size but I got the same results. I’m attaching the results.
Please help me in this regard.
Thanks in advance.
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Thank you for your comment and sharing the link. You are right the FE-BI and PML boundary box is better for such structures with two or more antennas.
Best Regards,
Behrooz
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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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Dealing with a helix antenna, made with flexible material and not rigid like using a PCB board or wire. At the beginning of the helix is too close to the ground plane, causing coupling. How can I get rid of this inductance problem, if I cannot use a PCB board design here.
Please advise.
Thank you
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Hello, if I understand you correctly, I can advise you to use high impedance "barriers" (EBG - electromagnetic band-gap), which provide increased isolation of the radiator from the environment. You can use them both behind the emitter and on the side. egards, Yu
Hello, if I understand you correctly, I can advise you to use high impedance "barriers" (EBG - electromagnetic band-gap), which provide increased isolation of the radiator from the environment. You can use them both behind the emitter and on the side.
Regards, Yurii.
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Hi, whenever i use circular array i get this error "Waveguide ports must be aligned with Cartesian coordinate planes for the transient solver"
Does anyone use circular array with waveguide ports? Any recomendation would be so helpful.
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As a proposal you can use regular polygons instead of a circle. Then you can use rectangular waveguides.
Best wishes
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I am using transient solution type in HFSSv15, and two same UWB Antennas are in far field of each other. One antenna is transmitting and other antenna is receiving antenna.
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I don't think so , you have to use a Matlab script to calculate it
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Could I please get the guidance on Helix antenna operated from 1.5 - 1.8 GHz. I am designing in hfss and not able to cover 1.5 GHz. Could I get papers or suggestions on numbers I use to cover this freq. please?
Thank you.
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Thank you Hassan Nasser and everyone
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I am looking for list of items in order of priority divided in three categories:
1. Must have items
2. Important items
3. Good if you have it items
and I am looking for tentative costing that each of the items would cost.
Thank you.
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1. Simulation software -- I would not get too paranoid about picking the absolutely best software package. They are all very good these days. My group uses Ansys HFSS, but there is also FEKO, CST, and so many more. Consider also developing your own simulation codes that can perhaps simulate special cases much faster.
2. Ability to manufacture antennas -- As much as possible, you want to be self-sufficient. Consider developing some capability to manufacture your own antennas. Perhaps that manufacturing method would give you unique capabilities that you could exploit. Maybe you get a 3D printer and work on all-dielectric antennas.
3. Ability to test antennas -- This is critical. At a minimum you will need a vector network analyzer and all the various cables, connects, adaptors, amplifiers, etc., that you will need to test and characterize your antennas. Consider getting or making a robotic platform for measuring antenna patterns. Can you also build an anechoic chamber? You would be surprised how much you can get away without having a chamber.
4. Photography & Graphics -- You will want to show off your antennas and also draw out new ideas. Consider getting a good camera and maybe a photo booth for good lighting. Get good at generating graphics to propose new ideas.
There are lost more, but I think these are the must-have items. Hope this helps!
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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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Hi, i am trying to perform SAR analysis in CST but the problem is after simulation in the post-processing section the SAR tool is not activated. Therefore i cannot get the results. Do you have any idea why? I put the picture below.
Any suggestion would be so helpful. Thanks in advance.
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Good question
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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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Need suggestions on how to do impedance matching on helical antenna? I want the antenna to be as light as possible so not going towards the balun right now. using a resistance may decrease the efficiency. Please guide
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Hello,
I do agree with Prof. Lema and Prof. White, that never use resistance for impedance matching. Actually, mismatch loss can be calculated using commercial software, so it will be easy to analyze the antenna matching impedance.
Few references are attached.
Thanks,
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How can I know how much power an antenna can handle? I know P = I^2*R, but here I only know R = 50 ohms. how to determine, this antenna can handle this much power? I am working on dipole and helix antenna.
Thank you in advance.
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You got a number of good answers and I want to make somethings more clear.
The antenna has certain specific resistance which is the radiation resistance Rr and has also some loss resistance Rl
So the input power P= I^2 Rt , Rt=Rr+Rl
I is the effective value of the current.
So, as a rating of the antenna one must construct it to withstand the maximum current in the antenna conductors. This is due to thermal fusing effects of the wires.
The other rating is the maximum voltage that can be applied on the antenna
where P= V^2/Rt
So the antenna must be constructed to withstand the maximum voltage defined by the maximum power the relation given above. The maximum voltage is limited by the breakdown of the gap between the two poles of the antenna as these two points are the nearest from each other.
These simple analysis may answer your question in a simple manner.
Best wishes
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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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Hi, ive desined an array of antennas with 8 elements. When i sımulate it i got this error message in CST "Waveguide ports must be aligned with Cartesian coordinate planes for the transient solve". The desingn is like that below. Any idea would be so helpful. This is my 1st time to use array so i kinda dont know what to do. Thanks in advance
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Hello,
one file is attached.
It may be helpful for you.
Thanks,
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Easy understanding of antenna design.
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You can also use MMANA-GAL, but only for wired antennas.
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I exported my design to dxf file but in the dxf file it only shows the drawing and no dimensions. How can I add dimensions in the drawing in the dxf file while exporting in cst?
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The local coordinate system u v plane has to cut through the thing you want to export. What that u v plane intersects is what will go into the dxf or gerber file.
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Directivity of an antenna is defined w.r.t. peak power direction. What if I want to know the directivity value at a specific coordinate point (X.Y or spherical coordinates) from the antenna. I want this directivity value to be plugged in the path loss equation, to find the path loss at a specific point from a BS. This point can be outside the main lobe of the antenna.
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Directivity (D) and gain (G) are two different antenna parameters. The purpose of the former is to show how well the antenna suppresses the sidelobes (unwanted propagation) while the latter is for provided peak gain. Both are used in antenna
design. They are related to each other with an antenna efficiency factor, i.e. G = e*D. Since e is almost 1 for the most current antennas, these two are used interchangeably in the literature.
The absolute antenna gains are already in the free space path loss equation. The received power is Pr = Pt + Gt + Gr - L where Pt is transmit power, Gt and Gr are the receiver and transmitter antenna gains and L is the path loss, all in dB.
Here Gt and Gr depends on the angle. The correct usage should be Gt(p,q) where p and q are azimuth and elevation angles. Similarly, Gr(r,s). Assuming the local coordinate systems of transmitter and receiver perfectly aligned with global coordinate system, then Pr is a function of these 4 angles, i.e. Pr(p,q,r,s).
If you know Gt(p,q) and Gr(r,s) for any angular point, Pr can be calculated. I believe that was your question.
Please see following for further details:
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I have designed a wearable microstrip antenna for uwb aplication. I have considered human tissues in my design and simulation(1mm skin 3mm fat 10mm muscle) but when I run this simulation it stops and error message says: out of ram. My ram is 4gig. How can I solve this problem?
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With my limited knowledge on HFSS, I would like to suggest few steps which can solve this problem.
1. Out of RAM issue can be solved if we somehow reduce the number of tetrahedron. If reduce the size of radiation box, a large number of tetrahedron can be reduced.
2. If 3D geometry is used to draw the ground plane, make it a 2D object, instead of 3D. It will also reduce the number of tetrahedron
3. All this process to other object if possible.
4. One task manager and delete unnecessary process. XP and windows 7 can run with 24 and 49 (45 to 54 avg) number of process. Try to obtain this number first, then open your HFSS and run the simulation.
5. If the problem is still not solve, try to use lower version of HFSS and draw your geometry therein and apply steps 1 to 4.
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in modal analysis (eigenmode CST) of unit cell , we obtain modes
what is the relation of these modes with TE and TM ?
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Within a structure, the eigenmodes correspond to all possible field distributions. Some of or all of these eigenmodes may get excited as soon as there is a nonzero projection between the incident fields on a field distribution associated with the eigen-fields. Eigenmode analysis will give you all possible field distributions. Now, once you will analyze your complete design in a full-wave analysis (time domain or frequency domain), based on your excitation source (port etc.) definition, and overall structure geometry, you filed distribution could be classified as TE or TM.
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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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Hi, I'm working with the CST software from 3DS and I use the farfield source functionality as an input for my study.
I managed to define the proper coordinates system (WCS) for the farfield source according to antenna position in the studied model. Nevertheless, once the simulation is performed CST expresses the farfield result in the general WCS of the model instead of the previously defined WCS coordinate system.
These results prevent me to perform a proper analysis of 2D half space plots of Copolarisation, Crosspolarisation etc...
Does anyone know a mean to fix this issue?
Thank you for any reply
PS : In order to ease comprehension of my issue I add pictures
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Actually you have use the two dimension code because there is aspecial code for each type
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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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I do not have much space in my design to put waveguide port with correct dimensions. Can i make it short and will waveguide port work properly in short dimensions? Like I have only 2 mm space to put waveguide port
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Hello,
First, form one more structure around your given structure with vacuum medium. Then select age and then take waveguide port on that selected ages.
Thanks,
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I have designed two same antennas, one is transmitting antenna and other is receiving antenna, both are in far field of each others and antennas are in face to face orientation.
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Hello,
As I use CST, but you can simulate any antenna in receiving mode with far field source and excite your receiving model either lump port or wave port and then right click on Field overlays in Project manager and then click to edit source option and change the solved magnitude for 0 W in wave port case and for 0 V in lump port case for the excitation of receiving antenna. In this manner you can analyze your antenna in receiving mode.
Thanks,
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I have submitted a paper in a journal where a primary radiator is surrounded by 36 periodic symmetrical structures similar to what is shown in the attached picture.
I have named it a metsurface patch antenna. The reviewer thinks it is it is a "CP patch antenna coupled with parasitic elements" NOT a metsurface patch antenna.
I want to know how we can differentiate between parasitic elements and metsurface?
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It's about propagation: desired effects, versus undesired effects.
Do you agree?
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Hello,
My question is what is the best and the most accurate method to simulate Radar Cross Section for simple objects (circular flat plate, rectangular flat plate, ... etc) using ANSYS HFSS19, I found some methods in google but some of that do not make sense while you thinking about it.
So if you got any good method to get accurate total RCS vs Aspect angle results using HFSS, please put that as soon as possible.
Thank you all.
Best regards.
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You can check out this document from ANSYS on FEBI boundaries, it could be of interest to you:
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I am working on edge fed spiral antenna , recommendation of papers on this is appreciated.
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Dear Sirs,
Everybody knows plane and spherical wave solutions of Maxwell equations, e.g for decaying plane wave E=E0*exp(-kx)*cos(w(t-x/v)). But seems to me they give the unreal situation that the wave amplitude is nonzero at different points of space at given time moment. Could you advise the experiment or natural phenomenon which produces such a wave in nature?
Maybe we have infinte speed of the EM interaction? Do you know any real solution of Maxwel equations which exists only in one space point at the given time moment? Maybe using delta function? Or maybe there is my mistake?
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Nice Dear Joaquin Diaz-alonso
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We can extract the data from HFSS using equivalent circuit export. Then how can we see the circuit in Ansoft designer?
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I am trying to export equivalent circuit model for FSS in hfss. But it's showing the W element model name must be suplied.
What is the problem can u explain?
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Dear All,
I want to know how do we create and simulate optical materials or anisotropic material in CST microwave studio?
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In ADS simulation, if I have the equivalent circuit (of the antenna), can I add the S-parameters curve (from HFSS or CST) to get the value of each element in the equivalent circuit by using the optimization function in ADS?
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Hello everyone,
I was just wondering what is the conception of an infinite ground plane when it comes to the metamaterials. For example, there are times that you need to use an infinite ground plane and I want to know how it affects the metamaterials' properties at the atomic level or how the electrons interact in the Physics point of view??
Or maybe, what are the interactions between E-fields and H-fields inside the structure??
Any answer would be a huge help...
Tnx
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Thanks for your response.
Actually, I'm aware of setting an infinite ground plane in CST, I was just wondering what are the visual ramifications of adding an infinite ground plane to the structure compared to a finite ground plane?!
Regards
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I need to design a phased array with freq. 2000 MHz to 2300 MHz specification. Thinking of linear array. Directivity should be high like 20 dBi and circular polarization.
Can you please advise me ? I need a head start please
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Dear Meenakshi Kohli,
I suggest you read the attached articles and his references. I believe it will help you.