nec coax simulation

Hi Folks:

I'm looking for a coaxial cable antenna simulator, that can be able to simulate collinear antennas made with coaxial cable such as RG58, RG213 etc.
Softwares that can simulate transmisson lines stubs are also welcome.
In URL below you will find the kind of antenna that I want to simulate.

http://www.rason.org/Projects/collant/collant.htm

Thanks in advance

No Fear[/b]

I'm looking for waht you need,
Do you have experience about squared or rectangular coaxial lines?
I'm looking for equations about RF losses for that structures....
Hope we can exchange ideas and materials.

Regards
Lupin

Hi Lupin:

Well I have some experience what you need. Coaxial lines I usually use for make RF dividers etc.
If you need some help about that, please, let me know.

Regards

No Fear

I'm working with all types of antennas for 2,4 GHz. I'm use the NEC and EZNEC simulator for my designs, with this soft is very simple the simulation but you have that very much knowledgement about RF and antennas.

Chao
Dienal

Do not expect to get the 9 dB gain indicated for two reasons. The outer conductors which radiate are not a half wavelength long and the 9 dB figure is for elements spaced a wavelength apart. Be happy with 5 dB. The other problem with this type of antenna is frequency dependent radiation angle. Also the impedance bumps at each joint will cause reflections.

Making this antenna is still a fun project.

You should be able to analyze this antenna by hand. First find the radiation pattern of one element and then apply the array factor.

dienal

Eznec, elnec, nec4win, necpro, necplus etc are nec/mininec routines based program and have some difficult to simulate LPDAs and corner wires such as cubical quads etc.
They work fine with vertical, yagis, corner reflector antennas. But most of them do not simulate transmission lines, unless transmission lines used for feed the antenna elements.
What I am looking for is a program that should be able to input the coaxial cable features such as vp, permissivity, resistance of conductors etc and the connections between the coaxial cable pieces ( normal or reverse ) such as eznec.
After I could place the source any length of coaxial cable and simulate it such as a simple antenna, as I do on nec based programs.
I would like the program provide me the impedance, VSWR, gain, and radiation patterns of the coaxial cable antenna.
Thanks for your interest;
Regards

No Fear :D

Dear flatulent:

Of course the guy who wrote these article was very very optimistic but lets considering the following facts:

1o) The collinear array should have:
a) Half wave dipoles
b) spaced between a half wavelength end to end.

2o) Feed the elements in phase to a 0o elevation pattern or not in phase to down/up tilt radiation pattern.

3o) One element = 0dBd
Two elements = 3dBd
Four elements = 6dbd
etc:

So lets consider that we'll use a 4 element array: Ideally we'll get 6dBd, that mean 8.15dBi.
Using coax cable the vp for polietilen is around 0,66 and the and the foam cables around 0.82
If we use foam instead polietilen dieletric we will approximate the ideal gain of a 4 element collinear array.
Do not forget, the guy add a 1/4 wavelength whip at the top of array so a little current more will be added to the total field pattern.
My question is: Do you know any software that is able to simulate this kind of antennas ? Do you have any literature about this ?
Thanks in advance
Regards

No Fear :D

Sounds like a job suitable for FEK0 or CST.

Cheers,
Ele

The gain of colinear antennas goes up by 3 dB per doubling when the tips of the dipoles are 0.4 wavelengths apart or more. If they touch the gains goes up by 1.6 dB per doubling. You can find this in several ham radio handbooks. One way to think about it is that the capture areas of each dipole overlap.

I have seen this antenna in ham magazines and books about once per 10 years. This is why you are having trouble finding literature on it.

I do not know which program can help.

I think that the problem is that the VSWR depend of the impedance adaptation of antenna and it depend the your design.
I don't think that the soft exist but I need it too.

Best regards,
Dienal