257 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 :: 19.08.2010 21:18 :: skwok :: Replies: 0 :: Views: 971
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 :: 19.11.2010 20:14 :: Kohi_boy :: Replies: 6 :: Views: 1676
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 :: 13.12.2010 10:20 :: vfone :: Replies: 2 :: Views: 1594
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 :: 11.10.2003 04:25 :: jsp :: Replies: 5 :: Views: 2782
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 :: 26.02.2004 15:03 :: rfmw :: Replies: 12 :: Views: 1816
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 :: 19.06.2004 12:15 :: 105s :: Replies: 6 :: Views: 1905
Put the width of the port same as the dimension of ur dipole...the length can be less than 0.1 lambda...
Electromagnetic Design and Simulation :: 20.11.2004 07:22 :: sonubal :: Replies: 7 :: Views: 1491
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 :: 13.01.2005 16:55 :: rfmw :: Replies: 4 :: Views: 1526
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 :: 06.12.2004 14:28 :: Mica188 :: Replies: 4 :: Views: 1614
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 :: 06.12.2004 17:37 :: flatulent :: Replies: 1 :: Views: 3270
in ie3d, can i define the plane-wave excitation and set a dipole as receiving antenna, so to get different current distribution with different load?
I had try in this way: first, finish the geometry of dipole and define a Horizontal Localized Port in dipole along with a Plane-Wave Excitation and run; Second, in modua i define the (...)
Electromagnetic Design and Simulation :: 16.03.2005 04:59 :: wusen :: Replies: 3 :: Views: 1169
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 :: 27.04.2005 11:28 :: flatulent :: Replies: 9 :: Views: 4157
If you want to measure the input impedance (S11) of the dipole, you'll have to use (or design) a balun. The dipole is a balanced antenna and cannot be measured as a single-ended device, e.g. a resistor, etc. Once the balun is ready, the "easiest" way is to design a TRL calibration kit and enter its data into the network analyzer.
RF, Microwave, Antennas and Optics :: 29.09.2005 04:36 :: jabidof :: Replies: 5 :: Views: 1547
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 :: 04.11.2005 04:18 :: vfone :: Replies: 6 :: Views: 2143
How to calculate the mutual impedance between two dipoles when using MoM technique?
My method is below: while dipole_1 is excited, dipole_2 is loaded by a resistance of ZL which value is as large as 1e8_omega to guarantee the open-circuit of dipole_2. So Z21=ZL*I_2/I_1, where I_2 and I_1 is the terminal (...)
RF, Microwave, Antennas and Optics :: 28.11.2005 11:03 :: wusen :: Replies: 5 :: Views: 2097
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 :: 10.02.2006 19:25 :: antp :: Replies: 1 :: Views: 1303
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 :: 29.05.2006 23:29 :: heedavid :: Replies: 4 :: Views: 1607
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 :: 20.04.2006 15:02 :: vfone :: Replies: 2 :: Views: 998
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 :: 26.04.2006 11:43 :: wusen :: Replies: 0 :: Views: 1186
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 :: 16.05.2006 07:36 :: nataliezhang :: Replies: 0 :: Views: 1171
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 :: 24.05.2006 03:35 :: Sceadwian :: Replies: 0 :: Views: 545
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 :: 31.05.2006 09:45 :: nataliezhang :: Replies: 7 :: Views: 1191
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 :: 15.07.2006 05:40 :: IanP :: Replies: 2 :: Views: 575
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 :: 21.07.2006 06:58 :: yuyu :: Replies: 3 :: Views: 4007
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 :: 07.08.2006 18:11 :: sunyvel :: Replies: 3 :: Views: 1120
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 :: 18.12.2006 12:08 :: jallem :: Replies: 8 :: Views: 3501
If your dipole did not come with a coax connector, you will need a balun so that you can connect it to the VNA
RF, Microwave, Antennas and Optics :: 22.12.2006 23:12 :: boy :: Replies: 2 :: Views: 791
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 :: 26.01.2007 04:16 :: blue_electron :: Replies: 1 :: Views: 1265
is this a printed folded dipole?
need more details. a picture might be very helpful
RF, Microwave, Antennas and Optics :: 31.01.2007 12:17 :: kato01 :: Replies: 3 :: Views: 799
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 :: 31.03.2007 11:44 :: vfone :: Replies: 3 :: Views: 1099
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 :: 26.04.2007 01:17 :: mns :: Replies: 0 :: Views: 839
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 :: 30.04.2007 01:43 :: Manas Sarkar :: Replies: 2 :: Views: 1262
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 :: 12.05.2007 09:01 :: me_user :: Replies: 2 :: Views: 474
04 Jul 2007 18:08 dipole antenna close to metal ground plane
i am using CST to model dipole antenna which is lying parallel to metal ground plane. i want to study the effect on antenna characteristic by varying the height of dipole over ground (...)
Electromagnetic Design and Simulation :: 04.07.2007 15:18 :: shahid78 :: Replies: 4 :: Views: 1939
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 :: 16.03.2008 16:18 :: cyprus :: Replies: 9 :: Views: 1475
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 :: 19.03.2008 19:08 :: johnyeoh :: Replies: 1 :: Views: 1645
Sometimes a full-wave dipole is prefered if directivity is important. However full-wave dipole has high impedance (400-500Ohms), so a transformer si necessary when feeded by ordinary 50Ohm system.
RF, Microwave, Antennas and Optics :: 17.04.2008 10:46 :: rfmw :: Replies: 4 :: Views: 1759
I have 2 problems in FDTD to get help.First thank you for your reading.
1. Zin(w)=V(w)/I(w), how to locate the contour of H for I(t)? Take a dipole as an example. The contour should be around the feed gap or around the arm?
2. When we calculate a strip dipole (thickness=0), a contour for I(t) is also needed.Should I include the H components a
Electromagnetic Design and Simulation :: 18.04.2008 05:01 :: Players :: Replies: 2 :: Views: 1221
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 :: 22.04.2008 15:14 :: guytoub :: Replies: 7 :: Views: 683
does any one have code of matlab so i can get the results of the gain in differnt wave lenghts and the input impedance ...... i have got the code to get the graphs of the pattern radiation and its working hope one of the friends can send me
or at least give me some basics thanks
Electromagnetic Design and Simulation :: 03.05.2008 01:24 :: cyprus :: Replies: 1 :: Views: 2011
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 :: 10.06.2008 09:59 :: thegame2008 :: Replies: 15 :: Views: 1488
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 :: 21.08.2008 02:01 :: parameswari :: Replies: 1 :: Views: 698
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 :: 30.08.2008 01:43 :: abc123 :: Replies: 1 :: Views: 817
Hello I am interested in learning the basic theory of dipole antennas, and be able to design and build one, but I have no ideal how do I get started with it. Can anyone help me with it? Any step by step tutorials to starts with >?
RF, Microwave, Antennas and Optics :: 31.08.2008 08:43 :: raylim :: Replies: 3 :: Views: 693
I'm working on a project about designing of UHF RFID tag antenna, I've searched
many articles,but few were found on microstrip dipole antenna, lots of dipoles antenna are not the type of microstrip. because we hope the back of the antenna is metal ground , that the antenna could be little affected by metal ,water and so on.
RF, Microwave, Antennas and Optics :: 06.11.2008 20:39 :: l.j.zheng :: Replies: 6 :: Views: 2653
I saw a paper on dual band antennas where they used two dipoles under one feed where the other is about half the size as the other so that one works at f0 and the other at 2f0.
edit: I attached the paper. Hope it helps. :)
RF, Microwave, Antennas and Optics :: 05.02.2009 11:13 :: thered :: Replies: 5 :: Views: 919
Here is the Antenna specification...
RF, Microwave, Antennas and Optics :: 21.04.2009 07:27 :: aq_mishu :: Replies: 16 :: Views: 4163
4:1 balun it will match 50 ohms to 200 ohms. The usual impedance of a folded dipole is somewhere between 200 and 300 ohms. In your simulation you get much smaller than this.
RF, Microwave, Antennas and Optics :: 06.05.2009 03:04 :: vfone :: Replies: 5 :: Views: 2037
First you need bandpass filter , after RF power amplifier .
1000 feets needs only 1 watt.
And easiest antenna 1/2 wave dipole.
RF, Microwave, Antennas and Optics :: 15.06.2009 22:33 :: brumi :: Replies: 1 :: Views: 534
You can use the fields calculator to calcuate the complex current and then knowing the magnitude and phase of the voltage you can calculate the impedance. I have been trying to do this with a dipole my self. Our set ups sound similar but I am just using a voltage source between the two cylinders and then measuring the current right at the center of
Electromagnetic Design and Simulation :: 17.07.2009 14:24 :: Spinoza :: Replies: 4 :: Views: 1542