1000 Threads found on edaboard.com: Dipole Impedance
I have made s simple dipole with lumped port at center and variable air box size.
The impedance changes quite a bit versus air box size.
I think HFSS recommends at least 1/4 lambda from antenna element.
Zreal changes from 82 ohm to 95 ohm when size increases from 1/4 to 1 lambda at 1GHz.
The minimum Zreal at 82 ohm is when size is exac
Electromagnetic Design and Simulation :: 08-19-2010 21:18 :: skwok :: Replies: 0 :: Views: 980
A resonant dipole impedance is about 67ohm with length about 95%+ of halfwave length.
73+j42.2ohm is at half wave length including the conductor diameter (thickness) and input gap.
Electromagnetic Design and Simulation :: 11-19-2010 20:14 :: Kohi_boy :: Replies: 6 :: Views: 1687
You need to match the 75 ohms dipole impedance to 50 ohms, and also you need a balun transformer from balanced to unbalanced (assuming you are using a single-ended input
RF, Microwave, Antennas and Optics :: 12-13-2010 10:20 :: vfone :: Replies: 2 :: Views: 1673
I agree with a_aziz and loucy. Simulating a half-wave dipole in hfss showed that a radiation boundary distance from the structure has significant influence on the dipole impedance, while not so much on radiation pattern. Anyway, put your rad. boundary as far as possible (2 lambda) to get good results on both...
Electromagnetic Design and Simulation :: 01-13-2005 16:55 :: rfmw :: Replies: 4 :: Views: 1542
I'm interesting to know if it is possible to measure the impedance of a dipole antenna with a VNA. I'll appreciate if someone can suggest me any link or reference where I can read about this topic.
RF, Microwave, Antennas and Optics :: 12-22-2006 19:52 :: rloo :: Replies: 2 :: Views: 799
analysis of mutual impedance between straight dipoles are readily available. but can anybody help me in finding mutual impedance between folded dipole and straight dipole? is there any paper or reading material where i may get general relations of mutual impedance between folded (...)
Electromagnetic Design and Simulation :: 04-26-2007 01:17 :: mns :: Replies: 0 :: Views: 852
Please this paper :
Input impedance calculation of dipole antenna using FDTD method
Wenhua Yu , Xiaoling Yang , Yongjun Liu , Raj Mittra , Yongquan Lu , Pai Wang , Qing Che , Rui Lu
Microwave and Optical Technology Letters
Volume 50 Issue 9, Pages 2335 - 2337
Published Online: 18 Jun 2008
Electromagnetic Design and Simulation :: 08-29-2009 08:51 :: medaziz :: Replies: 2 :: Views: 1369
hello, i am working on electrically small dipole. now i'm confused how to measure the impedance of small dipole? hope your opinion. thanks.
RF, Microwave, Antennas and Optics :: 01-03-2010 08:51 :: zhangm79 :: Replies: 1 :: Views: 656
You probably have found the problem by now.
Yoiur air box is too small, it should be at least 1/4 lambda.
Whne I made the box 200 x 200 x 200 mm, impedance dropped down to 83.5 + j*12.5.
This is still far from theortically 73 + j*42.
I made a circular dipole and it was the same problem.
RF, Microwave, Antennas and Optics :: 08-19-2010 20:11 :: skwok :: Replies: 9 :: Views: 2141
Probably is about a small printed dipole, and you can use a gamma match, which allow tuning the impedance match of the antenna.
RF, Microwave, Antennas and Optics :: 10-06-2010 03:16 :: vfone :: Replies: 5 :: Views: 1937
I have a RFID dipole antenna (microstip line), I want to measure input impedance and return loss so that I compare with simulating. But I don't know anyway. Could you please help me? Thank you in advance!
RF, Microwave, Antennas and Optics :: 10-16-2010 21:47 :: sudokubk38 :: Replies: 0 :: Views: 669
OK i have a dipole whose Zi changes due to close proximity of parasitic elements.
Complex input impedance is 150+160i .
And its surely complex (not 200 ohm ) due to parasitic effects :)
How can i achieve it practically.
Can Quarter Wave transformer be used in this case. if it can how can i use it somehow with a balun. I m usin
RF, Microwave, Antennas and Optics :: 08-03-2011 18:21 :: usman_mahfooz :: Replies: 3 :: Views: 1025
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
Electronic Elementary Questions :: 01-21-2012 01:15 :: randy orton :: Replies: 0 :: Views: 515
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 (...)
Electromagnetic Design and Simulation :: 06-18-2012 03:25 :: kae_jolie :: Replies: 0 :: Views: 529
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
RF, Microwave, Antennas and Optics :: 02-14-2013 11:31 :: mersault :: Replies: 6 :: Views: 1210
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.
Electromagnetic Design and Simulation :: 06-22-2013 05:48 :: FvM :: Replies: 25 :: Views: 1049
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 (...)
Electromagnetic Design and Simulation :: 06-20-2014 17:46 :: mingquanyuan :: Replies: 0 :: Views: 413
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 (...)
RF, Microwave, Antennas and Optics :: 07-09-2014 12:44 :: Kodomer :: Replies: 9 :: Views: 559
i have some question about the dipole antenna design
suppose u have tx output 50ohm
and matching 50 to 300
at that point two lamda/4 line then what should be the imp of the elements of just for electrical length it should be quarter wave
thanks in advance
RF, Microwave, Antennas and Optics :: 10-11-2003 04:25 :: jsp :: Replies: 5 :: Views: 2794
First I should mention that I'm an almost total beginner at h/f/s/s.
I'm trying to get a directivity pattern and input impedance of a standard very thin lambda/2 dipole in h/f/s/s v8.
I drew two (perfect conductivity) cylinders on the Z-axis with a small gap between them and altogether length is lambda/2 at the frequency of interest.
Electromagnetic Design and Simulation :: 02-26-2004 15:03 :: rfmw :: Replies: 12 :: Views: 1828
anybody can tell me how to denot the self and mutual impedances of radiating elements?I want to simulate the lof periodic dipole antenna in matlab.thanks!
RF, Microwave, Antennas and Optics :: 06-19-2004 12:15 :: 105s :: Replies: 6 :: Views: 1927
I'm a little bit confuse. Concerning the input impedance of an antenna, I have excited a dipole with a pluse (gaussian). The output data at each frequency is associated with one input impedance. Is this mean that to have that energy radiated I have to match this impedance to the antenna ? For example, the input (...)
Electromagnetic Design and Simulation :: 12-06-2004 14:28 :: Mica188 :: Replies: 4 :: Views: 1633
The impedance is determined by the physical dimension ratio of the diameters of the two surfaces across the dielectric as well as the dielectric constant. impedance is independent of length. The cable should have a model number printed on it. If not and the center conductor is solid the impedance is probably 75 ohms.
Your idea of the (...)
RF, Microwave, Antennas and Optics :: 12-06-2004 17:37 :: flatulent :: Replies: 1 :: Views: 3307
In coaxial cables 50 ohms can be conveniently made. It is difficult (because of the log radius ratio) to get below 30 and above 90 ohms. Many of the parameters of maximum power and minimum attenuation were for air dielectric cable and do not apply to plastic dielectric cable as commonly made today.
In the early days of HF and below it was comm
RF, Microwave, Antennas and Optics :: 04-27-2005 11:28 :: flatulent :: Replies: 9 :: Views: 4176
I would like to ask that how to measure a dipole antenna that don't have gnd plane?
RF, Microwave, Antennas and Optics :: 09-20-2005 05:36 :: samtsui :: Replies: 5 :: Views: 1554
dipole is a balanced antenna and you need a balun (BALanced to UNbalanced) to feed it.
There are a lot of types of baluns that you can use:
After that just connect the unbalanced end to the Port 1 of your Network Analyzer and measure S11 of the antenna.
RF, Microwave, Antennas and Optics :: 11-04-2005 04:18 :: vfone :: Replies: 6 :: Views: 2176
I have a similar problem, as in
The question is:
how correctly to define port on single-layered PCB for dipole antyenna model in free space without ground plane using ansoft designer
It seems to me, the input impedance of antenna 0.257 x 50 = 12.85 Ohm on resonant frequency 6.8 Ghz is too small
Electromagnetic Design and Simulation :: 02-10-2006 19:25 :: antp :: Replies: 1 :: Views: 1322
I'd a quick scan through your structure, so I'll just give a few opinions.
Is that a monopole or a dipole you're simulating? Cos' the hf$$ structure looks like a quartered-up (you're making use of the image planes, right?) coax-fed monopole with curvy ground plain.
So, with respect to a pretty decent monopole simulation in H
Electromagnetic Design and Simulation :: 05-29-2006 23:29 :: heedavid :: Replies: 4 :: Views: 1629
The impedance of a dipole in free-space is approximately 72 ohms.
The impedance of a microstrip dipole is affected by the substrate.
To match the dipole you need a balun.
RF, Microwave, Antennas and Optics :: 04-20-2006 15:02 :: vfone :: Replies: 2 :: Views: 1009
How to calculate the reactance of a half-wavelength dipole with infinitesimal radius?
The results otained from MOM precedure show that when the radius decrease from 0.005_lambda to 0.0000005_lambda, the impedance will be changed from 97.3014+41.3625i to 77.4771+43.5490i; it seems the reactance, that is, the imaginary part of the (...)
RF, Microwave, Antennas and Optics :: 04-26-2006 11:43 :: wusen :: Replies: 0 :: Views: 1203
who has the experience of meander line dipole antenna?
i am looking for the publication of "resonant frequency and radiation efficiency of meander line antenna", "impedance characteristics of small meander line antenna", and "input impedance increase of a very small meander line antenna". it is urgent and please help me.
RF, Microwave, Antennas and Optics :: 05-16-2006 07:36 :: nataliezhang :: Replies: 0 :: Views: 1189
This is a multi disciplinary question so I hope it fits in the General Electronics forum.
I have a micro controller (Atmel AVR tiny15) which has a high speed internal PLL synthesizer which generates "flat out" a 12.8mhz signal on an I/O line. I personally have no method of viewing the waveform this generates however I do have a friend that has a 1
Electronic Elementary Questions :: 05-24-2006 03:35 :: Sceadwian :: Replies: 0 :: Views: 558
could anyone help me on antenna measurement?
1, how to connect a dipole with VNA?
2, the antenna is designed for a chip in RFID system. should i measure it with chip or without chip? what is the difference?
thank you very much.
RF, Microwave, Antennas and Optics :: 05-31-2006 09:45 :: nataliezhang :: Replies: 7 :: Views: 1211
Technically, antenna impedance is the ratio at any given point in the antenna of voltage to current at that point. Depending upon height above ground, the influence of surrounding objects and other factors, our quarter wave antenna with a near perfect ground exhibits a nominal input impedance of around 36 ohms. A half wave
RF, Microwave, Antennas and Optics :: 07-15-2006 05:40 :: IanP :: Replies: 2 :: Views: 583
The attenuation of a coaxial cable is the lowest when impedance is about 77 ohm. Further a dipole antenna has a real impedance about 73 ohm. Therefore for CATV, where attenuation is important, a cable of 75 ohm seems a right choice.
Anyway, another important feature is the power handling capacity; it is possible to show that the maximum (...)
RF, Microwave, Antennas and Optics :: 07-21-2006 06:58 :: yuyu :: Replies: 3 :: Views: 4102
I am designing a halfwave microstrip dipole(not a patch antenna), which consists of two rectangular monopole strips of quarter wavelength each. I am simulating it in HFSS and I cannot achieve the 2.14dB which is the theoretical gain of a single dipole. My gain is around -2.5dB.
Can anyone suggest the possible reasons for the reduction in
RF, Microwave, Antennas and Optics :: 08-07-2006 18:11 :: sunyvel :: Replies: 3 :: Views: 1131
When I simulate a dipole I use a lumped port, and place the port between the 2 feeds and this yields correct results.
If I put a ground plane under the feeds (see attachment) and use 2 lumped ports (1 for each feed) then I get different results. I'm trying to make the short dipole a 2 port antenna because I'm trying to make a match
Electromagnetic Design and Simulation :: 12-18-2006 12:08 :: jallem :: Replies: 8 :: Views: 3544
my design is to match a folded dipole to a chipcon-based differential RF ports (86.5+j43)
since the radiation resistance of a folded dipole is about 300 ohms, then i need to match this to a differential line of 86.5.
my question is:
is it possible for me to use a coplanar line designed with an odd-impedance(?) that matches (...)
Electromagnetic Design and Simulation :: 01-26-2007 04:16 :: blue_electron :: Replies: 1 :: Views: 1278
is this a printed folded dipole?
need more details. a picture might be very helpful
RF, Microwave, Antennas and Optics :: 01-31-2007 12:17 :: kato01 :: Replies: 3 :: Views: 813
Changing the length of a dipole it will change the resonant frequency which is λ/2, and VSWR is getting higher outside the resonance.
RF, Microwave, Antennas and Optics :: 03-31-2007 11:44 :: vfone :: Replies: 3 :: Views: 1110
can anyone send me the detail theory of folded dipole ?
or is there any paper/book where i'll get the mutual impedance between folded dipole and straight dipole?
RF, Microwave, Antennas and Optics :: 04-30-2007 01:43 :: Manas Sarkar :: Replies: 2 :: Views: 1270
What software can modeling Resistivly-Loaded dipole?
I'd like to see what kind of process happend - periodic or aperiodic (as shown on the picture) on the dipole.
RF, Microwave, Antennas and Optics :: 05-12-2007 09:01 :: me_user :: Replies: 2 :: Views: 481
When a plane is too close to a dipole as in your
antenna, this is shorted out. This means the power
that is getting into the antenna is very small.
Although the power is small the directivity is based
on that small amount of energy, this is based on the
power effectively delivered to the antenna.
Electromagnetic Design and Simulation :: 07-17-2007 16:09 :: jallem :: Replies: 4 :: Views: 1971
i have seen a file in hfss used 30 ghz frequency to simulate the dipole antenna im thinking where can we use this this of antenna in real world can any one help me
Electromagnetic Design and Simulation :: 03-16-2008 16:18 :: cyprus :: Replies: 9 :: Views: 1491
I am new to HFSS. I am doing matching filter network to balance dipole antenna.
I know ADS but new HFSS.
Is anyone know how to assign an excitation differential port with Complex impedance to Coplanar Stripline which is <1mm next to each other?
Electromagnetic Design and Simulation :: 03-19-2008 19:08 :: johnyeoh :: Replies: 1 :: Views: 1663
hi i want to ask what is the differnces between half wave dipole and full wave dipole ......why they prefare half wave why not full wave or 1/4 or 1,5wave i hope to hear good answers thanks
RF, Microwave, Antennas and Optics :: 04-17-2008 02:14 :: cyprus :: Replies: 4 :: Views: 1813
have you got paper or design examples about printed dipole or calculation.
i would like to know how to make the matching with a 50Ω port .
i use IE3D
thank a lot.
RF, Microwave, Antennas and Optics :: 04-22-2008 15:14 :: guytoub :: Replies: 7 :: Views: 691
i have simulated the dipole antenna with different lengths and when i find the input impedance i find that i have some positive values for reactance and some negative values why i got these answers and how does reactance effect on performance of antenna
RF, Microwave, Antennas and Optics :: 06-10-2008 09:59 :: thegame2008 :: Replies: 15 :: Views: 1515
I have simulated 2 dipole above finite ground as given in that paper. in that paper they didnt mention abt type of ground , i used PEC as ground.I didnt give proper radius to dipole as given in paper. From my simulated result i could c 20 db difference between mine and paper result. Can anyone give me the reason 4 it. will ground plane and dip
RF, Microwave, Antennas and Optics :: 08-21-2008 02:01 :: parameswari :: Replies: 1 :: Views: 722
Anyone has info on the broadband dipole antenna, the one like a ball with two half cup together like a ball on the top and with a stick connected to the power meter used mostly in the EMI testing. any detailed info on how the dipole is formed? and connected ?
there are 1 axis and 3 axis types, is the ball shell part of the (...)
RF, Microwave, Antennas and Optics :: 08-30-2008 01:43 :: abc123 :: Replies: 1 :: Views: 824