antenna placement

[tlh0598]

When placing antennas close to one another (such as on an antenna farm), spacing or isolation is a concern. I think what needs to be considered is the propagation pattern of the antennas and as long as the main lobes and minimal side lobes reach an adjacent antenna, there should be adequate separation. Does this sound accurate? Does anyone have software recommendations to look at this sort of thing? Any other comments are welcome as well. I am trying to learn this subject and appreciate the advise.

 

[SolderingGunslinger]

Try posting to the Antenna & Propagation engineering forum.

Do a web search. For propagation software I have used V-soft, but I don't remember if they have a specific application similar to what you wish.

Good engineering practices dictate that transmitters and receivers located on an antenna farm be equipped with ferrite isolators and bandpass filters. In really high RF areas, some of the receivers might need to have notch filers for specific offending frequencies.

Good Luck,

I remain,

The Old Soldering Gunslinger

 

[Jasperv]

Keep in mind that the main factor is the frequencies. You can have one antenna to be used for a couple of frequencies at the same time,as long as you do some polirisation techniques and good filtering.Thus you can have two antennas next to each other as long as the frequencies are far enough appart to avoid interference.

 

[leonar40]

Check out Ansoft. They have a couple of packages that you could use to model antennas. One is called HFSS, and the other is called Maxwell.

 

[nbucska]

The propogation pattern shows the amplitude -- for the interaction of two antennes the phase is equally important
so you have to take the cable lengths into consideration, too. If the terminations are imperfect it is even more complicated.


<nbucska@pcperipherals DOT com> subj: eng-tips
read FAQ240-1032

 

[Tofflemire]

Hi All,

The general rule that we use when using antennas is keep the distance between them, so not to be a multiple of the wave lengths and have at least more than 1 wave length away from each other.

Tofflemire

 

[Higgler]

Give more details on your planned antenna farm. i.e. type of antennas and relative positions.
In general, antenna patterns degrade faster than VSWR does when you place two antennas next to each other.

Antenna patterns for the higher frequency (smaller antenna) usually degrade more than the lower frequency antenna (larger one).

Most antennas (dipole, monopole) quickly become open and invisible at slightly lower frequencies, but they are often very efficient above their operating frequencies.

Two omni monopole antennas next to each other on a car roof will result in the lower frequency antenna having good omni patterns and the higher frequency antenna having a null (or at least a dip, lower gain) in the direction of the low frequency antenna (as viewed from the high frequency antenna).

kch