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130 Threads found on Dipole Impedance
I would guess the transmission line Z is around 70ohm like other 1/4 wavelength dipole antennas. According to literature, it's more complicated. As a simplified idea, imagine that the characteristic feed line impedance loaded by the dipole elements equals the antenna input impedance. So it's always higher than the antenna (...)
I need simulate an antenna in HFSS for RFID. The internal impedance of IC at 915MHz is 12.8-j248 (NXP UCODE7). This is a serie impedance. To simulate this impedance I use a Lumped port with equivalent parallel resistance Rp ~ 4.837K and a capacitance of 0.7pF in parallel using a lumped RLC. Both in parallel connected to a (...)
Yes, you see almost real impedance of an antenna at it's center frequency, e.g. a dipole with length of lambda/2. An antenna is a distributed device, it has no physical L or C. In so far the quoted |Z| equation (not valid for Z) describes only a possible antenna equivalent circuit in a limited frequency range, not an actual antenna. As for the e
Hi, I was going through the induced EMF topic for finding the self impedance of a thin dipole in Balanis and he has writen this equation: V1 = (1/I1)* ∫ Ez*Iz dl where V1 and I1 are the voltage and current at the dipole terminals. Ez is the z directed electric field and Iz is the current at z distance from the origin. I could not (...)
Hi all, Please, How can I use Lumped element on a port for impedance matching purpose between a discrete port and dipole antenna in CST? How can I connected the Lumped element, discrete port and antenna together ? what I use to connected them?
the cpw port dimension may vary depending on the antenna type you using. what time of antenna you using? - - - Updated - - - what i mean by antenna type is dipole, monopole, PIFA and etc..
I do not have access to the fulltext of the following two papers. Anyone can help? Thx in advance! 1) R. F. Schwartz, Input impedance of a dipole or monopole, Microwave J., Vol. 15, p. 22, Dec. 1972 2) J. B. Andersen, Admittance of infinite and finite cylindrical metallic antenna, Radio Science, 3, 1968, pp. 607-621
Hi , Im simulating a yagi antenna with 6 elements with the haft-wavelength dipole driven element at 2.4Ghz using hfss v15. The radiation pattern, gain, directivity are as expected :grin: But the input impedance is somewhat i dont understand. As i know the input impedance of an dipole is about 73 +45j(ohm) but the Z (...)
Hello guys, I am currently making a design including a GSM module which has a 50 ohm impedance output for the antenna. However I am interested in using a dipole (73 Ohm img 43Ohm) antenna with this module. I have been searching around for either a dedicated , or discrete balun that can handle this transformation, with no luck. Does anybody h
................... P.S my dipole is precisely 50 OHM and so is the coaxial cable so no need for impedance transformation. I only need to eliminate the coax shield currents. How did you achieve that ? ... dipoles are 75 Ohms by nature ( folded ones 300 Ohms) ... what impedance matching did you do ? Dave
Hi, I am looking for a circuit to measure the voltage of a DNA dipole. The voltage could be around 125 micro volts. but it could be better to have a circuit which could detect between 50uV to 200uV. looking for earliest replies. thank you.
Your dipole has apparently a fundamental resonance (λ/2) at about 570 MHz. The order of magnitude looks plausible according to the dimensions. Review your design equations.
Hi I have a question about the Radiation Boundary in HFSS itself. I am simulating a dipole with a lumped port feed and I notice changes in the resonant impedance/frequency when I change the size of the Radiation Boundary. According to the design requirements, I gathered that the minimum distance of the radiation boundary away from the radiating
Hello, I am building a 2.4 GHz Yagi-Uda directional antenna for Wifi. I use a RG-58/U coaxial cable with 50 Ohm. I use the Yagi calculator of VK5DJ as a guide: The folded dipole has an impedance of 288 Ohm. The transmission line has an impedance of 50 Ohm. The impedances do not match, so impedance (...)
I have tried to simulate a half wave dipole with HFSS using PEC. The dipole is 38.75mm long with a small gap (0.4mm) between the two arms to allow a lumped port to be put there. So this should be a half wave at around 1.8GHz. But the imaginary impedance does not even reach 0 (smaller than 0). How can I determine the input resistance of (...)
Hi in literature sometimes we give the input impedance as a function of L / lambda0 (normalized length) Please, can someone show me how to do to plot it as a function of L / lambda in HFSS for whatever structure (e.g. for a dipole, or a patch antenna). of course I know how to do it as a function of frequency. Thanks
Not quite. That is contradictory. For a dipole you can choose 1/4, 1/2 and 1 wavelength. Resonance is non reactive just below theoretical due to fringing and thickness. more details here 1/2 wave is most common.
hi guys.. what happens to the feed resistance of an antenna when the reflector and the director are placed on either side of a dipole? what happens to the beamwidth when the number of directors are increased? what is the approximategain of a three element parasitic array? a circular polarised yagi enables the receiver to obtain signals from...?
You can get a formula for the complex impedance of the antenna from Wikipedia under "Short dipole" on the "dipole Antenna" entry. and there is a section on "General impedance can use a calculator on it. You will be looking to
how to design a co planar stripeline feed and integrate it to dipole antenna with reflector?. i have designed the antenna but it is showing a VSWR of 3 instead of 2 . need assistance for design and integration. impedance is 150 ohm and hence need to design the width of the feed and gap of the feed to the dipole antenna ant to integrate.
One-tenth wavelength dipole, 1.9 GHz on FR4 PCB. About 10 mm long antenna? Yes it is possible to design and impedance match a such antenna. Anyone can do it. Very few can do it and get reasonable performance. Good skills how to set up a VNA is recommended as short antennas and extreme impedances both requires good calibration to be able to (...)
I don't even know where xxx comes from. It's just putting in the said geometry (length and feed point) into the general dipole current distribution expression (4-56), page 170.
Clarification of terms. you say "dipoles are λ/2". At which frequency? How do you measure "mutial impedance" of antennas? In network analysis, mutual impedance involves a driving current source and open circuit voltage measurement, which is hard to implement in RF frequency range.
You are correct, your formula for gamma is only valid for Im(Zin) = 0 (that is Xin=0). You can see that when plotting the impedance on a Smith Chart. When there is an Im(Zin) part, the impedance moves towards the edge of the Smith Chart. Can it be that the length of the antenna is specified as the length of one half of the dipole? So (...)
Hello, I have simulated a dipole antenna at HFSS. Now, I would like to use it in a design at ADS. In this way, I would like to have a two-port block that would mimic the impedance frequency dependency of the antenna. Probably at port 1, the impedance should be always equal to 50ohms, while the impedance at port 2 should (...)
Antennas can be of any length related to wavelength. A good antenna must have an impedance matched to its feed line, and its radiation pattern is selected according to its use. Half-wave dipoles were found optimum in both aspects. In fact, 0.47 wavelength is the optimum dipole length.
Hello, I'm trying to make a dipole antenna for UHF (433 MHz). I have a 50 Ohm unbalanced output so I need to balance it and do an impedance matching to get the best performance possible. I bought some Minicircuits' ADT1.5-1 ( ) to do the job. I made a PCB, soldered the transformer and the legs of th
Hi there, I am working on printed dipole antenna array. I an new for XFDTD design, and I really need help. For making understanding, I started to design Microstrip ; one end I put feed component 50 ohms and put passive load 50 ohms on the other end. The result was as I expected. After that, I designed a patch antenna at 2.4 GHz and i
Hi, I'm pretty new to FEKO but as an assignment, our professor wants us to create a dipole and analyze it "over a broad spectrum" On his sample graphs he showed us a plot of the impedance vs dipole Length. I was wondering how to do this. I can create a dipole using a fixed length but I can't seem to figure out if it's (...)
Is your bow antenna above a ground plane, as this has large influence on input impedance? feeding a dipole off-center, will raise the impedance, but you get a large common mode component, that will increase the common mode current in the coaxial feed line. The common mode current contributes to the radiation pattern (mostly not desired). (...)
Dear all, I have a question about matching a printed folded dipole. I am working at 2.45GHz My antenna is connected to a 50 ohms /50 ohms balun, then connected to a 2-ports VNA, for s11 evaluation. At the frequency of interest, the impedance is Z; is this the impedance of the antenna seen from the VNA? Because I need to tune this (...)
I believe the HFSS Antenna Design Kit (ADK) can be extended by adding your own code, but does anyone have any instructions on how to do this? For example, lets assume I want to be able to design a folded dipole to have a specific impedance. One can achieve this by having the two sides of the dipole of a different diameter, and there are (...)
I have 5-element λ/2 dipoles spaced 0.1λ apart (they all show in the model...I am not using the Antenna Array Setup wizard). They are all excited with 1W each and the port impedance for each is 73ohms. After simulation, the power accepted is about half less than power incident. When simulating one half-wave dipole alone with 73ohms (...)
Hi everyone I want to use HFSS to design dipole phased array antenna. is there anyway to use Tschebyscheff coefficients for amplitude? in hfss----radiation----array design menu there is not any option to choose amplitude coefficient. would u please help me?
I've tried to simulate using HFSS a thin half-wave dipole which is immersed in a perfect dielectric with Er=81. (This is the same dielectric constant as water, but I used a perfect dielectric for the simulations to get a feel for the results, and to later see how much the conductivity of real water effected the antenna's properties). I c
Hi alberthyc, Could you share how you figured out where the remaining power went? I'm trying to impedance match a 5-element dipole array but with no luck. I tried to match it with Active Z re and im values, but I still get power accepted much less than power incident. Thanks.
I am trying to impedance match a 5-element dipole array in HFSS using the Active Z re and im values, but I am not getting good S11 with it. How do you achieve good impedance matching of array elements? Please help all you HFSS experts out there.
How does one obtain the active input impedance of a 5-element dipole phased array in HFSS? I am using the Active Z measurement and plot re and im values. Is this correct? When I do this I get different impedance values for each of the elements. Shouldn't the impedance values be symmetrical around the center array, for (...)
Hi all. I've been measuring my dipole antenna impedance at UHF band recently,i used single-ended two-port VNA and calculated the final differential impedance by some formula directly from S11/S22/S12/S21. Attached(the coaxial one) is my differential probe made by coaxial cable. Before measure the dipole,0603 100R resister (...)
Anybody in work on UHF RFID design? We've been discussing differential impedance measurement for RFID antennas or tag chips, one question still bothers me, which is below. As we all know,dipole has differential ports, as the load of antenna,the TAG CHIP usually has single-ended port. Such as NXP/Alien, the tag chips have only one RF port and
Hi, I am currently designing 433MHz half wave Printed dipole Antenna with input impedance of 50 ohm using Ansoft HFSS 13. The problem is, i can't seem to figure out how to efficiently place the ground plane in the design. This is because, either the simulated radiation pattern is severely distorted or my Z11 graph and smith chart is does not yiel
Do really not understand if you have a dipole or two independent monopoles, and if dipole, why try to measure it in two halves. Anyhow, during a part of the measurement are you measuring S11 for one antenna element and RF ground do then only consist of your cable shield? If move your hand along coaxial outer shield, does then S11 at VNA fluctuate?
Because the log periodic use a bunch of parallel dipoles, its impedance is actually lower than of a λ/2 dipole (which is about 73 ohms)
Folded dipoles with equal diameter wires in both parallel lines increase the impedance by 4x. This will increase the lowered impedance (caused by the parasitic elements) to be more nearly equal to 50 ohms and make the impedance matching to the coax easier.
Hello all I am trying to design a dipole antenna using HFSS. In my design i plotted a graph for input impedance Vs frequency and it seems that instead of somewhere close to 73 ohms i am getting it to 117 ohms which is way to can anybody take a look and tell me what is wrong with a design and how can i get a output close to 73 ohms?or th
Hello everybody, I'm trying to simulate a dipole with a voltage source in the middle of them. For that, I'm using a lumped port that is found in the middle of the dipoles, and it have the voltage that I want. But i'm having a very small input impedance. An I doing something wrong? I found to a model tutorial simulate that use the lumped (...)
I've tried to simulate a half-wave dipole in HFSS, using a perfect electrical conductor (pec). The dipole is 500 mm long in total, with a small gap between the two arms to allow a lumped port to be put there. So this should be a half-wave at 300 MHz. Using a wire radius of 1 mm, with a 1 mm gap between the terminals, the input impedance (...)
A quarterwave "whip" monopole will have an input impedance of Zin = 36.5 + j21.25 ohms at it's resonant frequency. A half-wave dipole would be 70 ohms. You can replace your antenna with one of these two loads, depending on what type of antenna you intend to drive. It should work as a first-order approximation.
Hi, i'm trying to calculate in HFSS the impedance of a tapered dipole at a distance x from the center. Is there a quick way to do it? Thanks, Gabriele
Hi, I simulated a simple dipole antenna in HFSS. When I wanted to look Zin in Smith chart it gave me this coordinate sistem. If I want to see S11 in smith chart the cookrinate sistem is good. Why?

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