Questions related to RF Engineering
I know that I should compare their actuation voltage, capacitance ratio, and S-parameters. Apart from the mentioned characteristics, are there any other ones that I should compare?
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?
Hello good time
What metals can be used in the design of high frequency devices such as Coaxial transmission lines , waveguides, coaxial to waveguide adapters? (Diamagnetic, paramagnetic or ferromagnetic)
For example, can I use tungsten rod , which has a magnetic permeability coefficient of 1, to build a coaxial transmission line? (What is the appropriate magnetic permeability number for the metal used to have low insertion loss(S21)?)
PCB dimensions are 30mm*18mm. Substrate: FR4 (1.6mm).
Frequencies of interests: 868MHz and 2.4GHz (Dual Band antenna)
Omnidirectional pattern idealy.
Hello to all
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
I am trying to simulate an antenna placed on a FR4 substrate (snapshot attached). PCB top and bottom layer is metal. For this case, to assign a port, I have just drawn a rectangle at the edge of the PCB having a width same as the feedline and length same as the PCB height.
Is it the correct way of assigning lumped port for my case (grounded CPW)? If not, would you please tell how should I assign the port accurately?
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
I have designed a bilayered structure on CST which is having copper patches as upper and bottom layers and a substrate sandwiched in between but I want LC equivalent circuit for the whole structure.
I have a DC/AC high voltage transformer to feed a spark plug to generate plasma using an arc discharge.
The output voltage goes up to 30kVpp and 400khz
When connecting one of the secondary of the transformer to GND at 5% of the breakdown (then the secondary is open circuit because spark gap voltage is under breakdown) high energy current is discharged to ground breaking Push-Pull circuit.
I have set a 150 ohms resistor to ground and measured 260mA.
The problem gets worse if the ground is connected to the Large plasma steel structure
I can not explain the problem using classical approach
Here is the circuit:
Is it possible to use a Dual polarized antenna instead of CP antenna? For example in RFID: Which antenna can detect most of the tag? Circulsr or dusl polarized antenna?
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.
I am using HFSS simulation to connect electric circuit (in series with resistor and DC bias) to metamaterial to study the response of the metamaterial to the external bias voltage. I do not know how to couple the external circuit to the metamaterial. Any help would be appreciated.
As part of my research, I need to couple a loaded, custom-sized, rectangular, waveguide (in which a hybrid mode propagates at 8.5GHz) to either a) a coaxial transmission line or b) to a standard X-band waveguide.
I need to understand the design and optimization processes for both including impedance matching and/or mode conversion as required.
What is the best, most efficient way of approaching such a task?
Any useful resources on the topic would also be very much appreciated.
I am unable to quantify the role of passive components when it is attached with the antenna. For various frequency bands like L,S,C,X the specifications of the active circuits changes but what will be the change in passive components and the antenna with respect to the frequency band.
Kindly give some answer or link , I am fully confused and I have to make a RF transceiver for demonstration purpose for the above mentioned frequency band.
If I get the block diagram with specs, it will be highly appreciated.
I hope I will get the answer at the earliest
I want to know the attenuation constant of a microstrip line. And I measured s11, s21, s22.
Can I draw attenuation of the line by subtracting both mismatch losses at the port and the load from s21 as shown below?
Mismatch loss at the port: sm1=10*log10((1-10.^(s11(:,2)./10)))
Mismatch loss at the load: sm2=10*log10((1-10.^(s22(:,2)./10)))
attenuation constant=ling length*attenuation
I am using HFSS to simulate a periodic structure which extends to infinity in one direction and finite in other (n x infinity array) for s-parameters. I set the boundary condition on top and bottom to be PEC and master/slave on x-direction and assigned wave port excitation but it doesn't work. Can you please suggest me a suitable boundary condition for my problem?
I used to run simulation for the antenna with lumped port till very recently.
However, realized that it is quite risky when it comes to monitor the real wave intensity and affect to other material.
However, every time when I try to run the simulation with wave port, error comes out.
even though it was run well on with lumped port.
i believe it was
Port refinement, process hf3d error: Port 1 is assigned to an internal face. Only allowed with lumped ports..
I tried quite many times to solve this problem.
But unable to fix it.
What I tried to do was make an antenna tuner on the loop antenna with 13.56MHz
Is there anyone able to help me with?
and respect all whom read this.
Many data sheets for power amplifiers state the P1O ( 1dB compression point) and Psat (saturated power) levels of the device. what is the difference between them, are they same?
I have done the simulations to find the s-parameters of EM waves for metallic (copper) wire array system ion COMSOL. The EM waves is reflected back and there is hardly any transmission. However, the phase of the transmission coefficient is greater than zero (figures attached). Can anyone explain why is that so?
I've got a bunch of antennas with varying VSWRs and dBi ratings, and a couple of standard SMA headers from various 2.4Ghz radios. I would like to learn how antenna selection will affect RF power and range.
I have calculated and plotted the dispersion relation for a cylindrical wave-guide partially loaded with an artificial dielectric. I now need to calculate and plot my cyclotron electron beam / wave-line on my dispersion plot. Can anyone explain how this is done?
I am currently doing a project to make a wireless sensor, which should have the following structure: overview.png
My task is to connect the double split ring resonator (DSRR) and vector network analyser (VNA) wirelessly. DSRR is a microstrip resonator whose resonant frequency shifts if liquid is introduced to flow through the capillary. Therefore, it can be used as a sensor to detect liquid.
I know there are several possible ways to achieve the wireless connection, but I am totally stuck.
I tried to use rectangular patch antenna as TX/RX antennas similar to the paper “Wireless Sensing of Complex Dielectric Permittivity of Liquids Based on the RFID” (but the paper uses ultrawide band microstrip dipole antenna). However, I failed, my CST simulation results show no resonance.
I used cross polarization, so cross talk is not a big issue?
In addition, I guess because the DSRR does not have a distinctive peak, the overall frequency response cannot reflect the DSRR resonance.
I am not sure whether my interpretation is correct or not, can anyone help me?
Moreover, my supervisors suggest me to use antennas with higher directivity. Is there any microstrip antenna with simple structure can achieve much higher directivity?
Furthermore, is it also possible to use nfc antenna or near-field antenna for the wireless connection? But I don’t know how to realise it with microstrip at GHz. Neither don’t I know how to build the LC tank if the DSRR has inductive impedance.
Please help me out
I need to calculate the dispersion curve for a cylindrical waveguide partially loaded with an artificial material. For reference at present I have papers by Brand (2006) and Rao (2007). Can anyone suggest:
a) Any other reference material that may be useful.
b) Any commonly used methods used to complete the calculation.
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)?
Thank you in advance.
How do I create a three port s-parameters matrix of a three port device from a two port s-parameters measured between each of its two ports assuming the third is 50 ohm terminated.
I have faced a problem regarding the thickness of copper layer. I have designed a feed network (100 ohm) in RO3010 (permittivity 10.2) at 865 MHz. At first it was designed by 35 um thickness of copper. Due to manufacturing limitation, I had to change the thickness of copper.
When I changed the thickness of copper layer then it showed completly different reflection loss.
At 865 MHz, the skin effect is 2.22 um . As far i know thar I have to take 3 times thicker than skin effect. But, at 18 um copper thickness, my result was not satisfactory at all.
It would be great if you can give me a suggestion about this issue
I gotta admit I am rookie in this field. In my current working, I am encounter with some problems, I designed transmission line, grounded coplanar waveguide, return loss is not bad but insertion loss is not what I expected. Then I changed it into conductor backed coplanar waveguide, I designed the space between each grounding vias as quarter wavelength which I read from an article, both the return loss and insertion loss is fine. But due to there is too many grounding vias, the cycling time for manufacturing is a problem. As I changed them half wavelength, the insertion loss is even worse than grounded coplanar wave guide. I wanna ask that is there any solution for that?
While performing harmonic balance (HB) simulation by using oscport in ADS, an unwanted oscillation is detected prior to my desired frequency of oscillation. ADS detects the first one and gives HB simulation results of the unwanted oscillation, and no result is found for the actual oscillation. Although the active component is properly matched for enough gain and unstability at the desired frequency, this problem occurs while performing HB simulation. I am expecting some suggestions on this issue.
I have 2 questions related to Microstrip Line characteristic impedance:
1) What would be the relation of characteristic impedance of a given microstrip line with frequency?
As effective permittivity increases with the frequency and gets closer to that of the substrate, according to formulae in Pozar Microwave Engg the characteristic impedance should decrease in my opinion. Could someone please clarify this?
An updated issue on the same is that according to a LineCalc tool in ADS, the Zc increases for a given line with increasing frequency which is exactly opposite to what I expected. Am I missing out on something here?
2) Why are there are 2 formulae for calculating Zc based on W/h greater or lesser than 1? (Reference Pozar Microwave Engg)
Does this mean that we can have 2 different possibilities to get say a 50 Ohm line on the same substrate for values of line width greater and lesser than that of the substrate respectively?
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.
I have measured data of antenna radiation principal cuts in Theta(Angle) / Directivity form. Now I want to interpolate both the E and H plane cuts to make 3D radiation pattern. But I don't know how to arrange data in MATLAB & then perform interpolation. And can we do it in MATLAB's curve fitting tool ?
im working on linear polarization in ISM band , and cross polarization will associate with co-polarization as side effect ,so is there any specific level form x-pol in that band ?
What is the main difference between dual band and dual radio?
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?
I have a GNSS RF chip. I should connect the RF pin to an antenna connector with a 50 ohm microstrip transmission line.
I calculated the RF track width and printed the PCB
Now I want to measure the track impedance to verify calculation and design.
Is there any measurement device for that?
*The frequency of RF signal is about 1.5GHz.
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.
RF transparent materials are materials where RF fields can penetrate with no heating happen. So far, I know some like Teflon, PPL, PVC, and ABS. They are made of plastics and have almost 0 dielectric loss factor. Anybody can suggest and give opinion about this.
In general, the microwave oven employs 2.45 GHz and most microwave ovens have similar cavity. As I guess, the transmitting length isn't finite. However, how about valid distance of the conventional microwave? Some people said that radio waves expand out using the inverse square law, meaning that the strength is 1/(distance squared). Then, how much distance is valid to increase temperature of target if there is no door and just with waveguide? If there is any scholar equation or base data about it, I hope to know that. For example, using the governing equation concerning with energy transmition of microwave, quantitatively calculate them.
Furthermore, recent commercialized microwave ovens have a stirrer in the wave guide. The stirrer do a role of microwave diffusion as I know. But it may interrupt microwave transmission or decrease the energy for target. Isn't it?
Hello everyone. Although it is well-known that near 30 dB gain should be dedicated to RF chain of LNA and mixer in an RF front-end, for sure the precise choice especially when designing a discrete system and to select the near-optimum components is strictly application dependent. what are the main considerations to choose this conversion gain? All answers are appreciated.
Can you share with me some thoughts on how I can accurately calculate the impedance of mesh grid?I have attached the picture of ideal structure I am interested in. Basically, if you lay a mesh on top of dielectric, how can you simulate surface or sheet resistance of the mesh?What software can I use to model this structure?Any publication/paper/book that I can refer to? The structure I am working with is more complicated, however, if I can figure out this, then it will be much easier to tackle my design effectively.
I appreciate all the inputs.
Is there any equation or mathematical expression to generate the radiation pattern polar plot of standard Horn antenna (say 25 dB, 20 dB)?
Waves can move at a speed of light. However, I am not sure if waves can travel more than its wavelength considering it is an open space.
I have designed a triband MIMO antenna for which MEG is one of the important parameters. I have difficulty in evaluating the MEG of the designed structure. I have designed and optimized using IE3D 14 simulator.
I am working on RF rectifiers. Tell me which book is more suitable for RF rectifiers. Many research paper uses non linear diode model for more precise results. I am new in this field.So tell, from where to start?
I am designing a rectifier at microwave frequencies. But I don't know the exact procedure to calculate Impedance of diode used in it. I also want to know that how to decide the microstrip line length and width between different lumped components.How to calculate load value.
There are various excellent literature's available that derive the power consumption model of a macrocell base station using number of sector, traffic load etc. as variables. But none of them considered the impact of antenna gain. This is surprising, as in practice antenna gain is common and varies with scenarios, BS types etc.
Why is the antenna gain not incorporated in the base station power models? If so, then how would I integrate it's impact on the existing models?
Please recommend differential amplifier with sensitivity (as low as -40dBm) and Gain above 20dB. Gain bandwidth from Dc to 1MHz?
Probing resonance of Dirac equation with complex momentum representation,in this PRL . How to get (4) by putting the wave function (3) into (2). Who can give the derivation process?
I am trying to design a planar to dielectric waveguide transition with a schematic as shown in the figure alongwith. Despite a good S11 at a particular frequency, the S21 is not that good. I would like to know how to find out the power radiated in CST for example to understand where the power is going. Note that I have simulated all lossy dielectrics as lossfree and used PEC for the microstrip patch, so I guess its either being radiated or going into higher modes. WOuld be very obliged to have your opinions on this.
Figure below: Port 1 is the input port for the Microstrip line feed and port 2 the output port above the waveguide.
Can we derive any conclusion on RF performance of device by seeing the transconductance or drain saturation current (Idss).
More specifically this question is on HEMT performance determination.
I'm designing a simple, lumped element low-Mhz level (1-100Mhz) detector circuit. But, I have some problems.
Before designing this detector circuit, I'd worked a Ghz and Sub-Ghz level RF/Microwave Energy Transmission project and I thought "I can use same RF schottky diodes for this application".
Unfortunately, I noticed the input impedance of HSMS/SMS series schottky diode are not suitable for impedance matching around 50 Mhz (1-100Mhz band). They can easily match around Ghz although.
I need to choose appropriate schottky diode around 50Mhz.
Which diode more useful for this situation?
How to design/simulate a planar balun for a passive double balanced mixer MMIC?
I have been stumped by a passive double balanced mixer for quit a long time. Problems mainly encountered are:
1. Space between microstrip lines (clearance) must be greater or equal than 5um (technology limit), however, lower insertion loss requires smaller space.
2. However I modify the microstrip line width(W), space between MS lines(S), number of turns(N), or length of microstrip line segments(L) of the balun, I can never achieve a balance output, i.e. , equal amplitude with 180-deg phase difference, and the insertion loss is much higher than .ideal 3dB(greater than 6dB).
3. Mixer realized with that balun suffers from a big conversion loss (greater than 10 dB) and poor port-to-port isolation and spur rejection.
4. Simulation results of the same balun model carried out with ADS and HFSS differs a lot, where HFSS yield much better results with lower insertion loss and phase unbalance.
1. How to design/simulate a planar balun for a passive double balanced mixer MMIC?
2. Why is there so much difference between ADS and HFSS simulation results?
3. Which one yields a more reliable result, ADS or HFSS?
4. Can anyone help me with this design?
Any suggestion or discussion is welcome. Thanks a lot!
I want to combine both of antenna and rectifier on single unit to have just 1 output
ThingMagic Reader M5e
10 dBm power conditions.
I have designed an antenna which is operating in certain range but the solution frequency is beyond that range...If I am changing the solution frequency in to that bandwidth range then the performance is not that much good as that of previous one. Kindly suggest me what to do ? I am using HFSS 14.0
why pulse modulation of repeller voltage (and consequently the output power) is required in reflex klystron while working in microwave laboratory, when continuous power can be obtained at a single frequency (without modulation)?
RF-based wireless energy transfer is attracting increasingly attention from wireless communications community. Simultaneous information and power transfer is a hot topic right now. Traditional information transmission may suffer from transmit oscillator jitters, e.g. carrier offset. Has any one considered their impact on wireless energy transfer? Are there any related materials on this issue? Thank you.