omnidirectional antenna [hlp neede]

[No one]

Hello;
Can anyone explain me about theory and applications of omnidirectional antenna?
please explain about different types of it. Also thanks if you provide me probable omnidirectional patterns. What books/papers describe omnidirectional antennas well?
No one

 

[ishtiaq]

Theres a book:-

Antenna and EM Modeling with MATLAB by Sergey N. Makrov

I havent tried it myself but it seems quite helpful at initial scan. Try it out.

You can get a lot of stuff here: h**p://file.21ic.com.cn/RFDesign/

You can also get in electronic format at edaboard/e-books forum

Thanks

 

[fbg]

hello

look this link and enjoy :

**broken link removed**


regards...

 

[dowjones]

hello,

please be more specific. omnidirectional antennas do not exist. "omnidirectionality" means radiation in all theta, phi directions, and all real antennas have some preferred directions (they are directive).

also, omnidirectional antennas do not have polarization information (radiation is the same regardless the polarization), and this does not either exist.

the unique omnidirectional source is a point source, which is a theoretical concept.

probably do you mean low gain antennas?

rgdz.

 

[fishyxl]

As you koow, an omnidirectional antenna is one which radiates equally in the horizontal plane. A classical one is the dipole antenna, which has a gain of about 2dB.

It can be realized in a lot of forms. For example, people often use coaxial cable to realize it. Recently ,people tend to ues printed antenna to make it. You can get a lot of literature on IEEE website.

 

[flatulent]

There are a variety of methods. Most of them have at least one null direction. Omni scientifically means all surfaces of a sphere. In engineering terms it usually means only all angles of azimuth.

The simplest is the vertical monopole. Next is the turnstile that is horizontallly polarized on the azimuth at zero elevation and becomes circular at the zenith. There is another phased array of four dipoles at 45 degree angles with respect to the horizon and spaced around a circle. There is a special phasing. This produces circular polarization at almost all of the scientific definition directions. You can see it in the famous Jasik antenna handbook. It was invented at the US RCA laboratories about 1935 for use at airport ground stations to communicate with airplanes. At least one dishonest ham as published it as his own invention in a ham magazine and it has gotten into some antenna software tutorials under his name.