connecting parallel antennas to increase gain

[deepak007]

antennas in parallel

hello

if i connect a second antenna parallel to my fm receiver antenna. will the gain increase? how many antennas can be connected in this way? what are the methods to increase the antenna gain? on what factors does the gain depend upon. i am a beginner to antennas.please suggest some practical books without complex mathematical equations and which can be easily understood.

 

[vfone]

Re: antennas in parallel

The gain of the new antenna will increase ONLY if there is a particularly phasing and distance between antennas. Just search the net for Phased Array Antennas.

 

[deepak007]

Re: antennas in parallel

can i use two whip antennas in parallel for my fm receiver?

 

[Eugen_E]

Re: antennas in parallel

You need to consider phasing, matching...
Make a λ/2 dipole, this is directional and gives a bit gain. You need to use a balun, coax and matching. It's easier to build an amplifier.

 

[biff44]

Re: antennas in parallel

I did some empirical experiments with two antennas connected at zero phase. One was horizontal, the other vertical polarization, but because they were electrically small ground planes, there was a lot of cross polarization pick on either.

At certain azimuths, there was a complete null. At others, there was no huge improvement.

In order to get my situation to work (omnidirectional for both polarizations) I had to delay one of the antennas by 90 degrees.

This was narrowband at 315 MHz.

 

[saif haider]

Re: antennas in parallel

Gain formula for antenna is
G=(4*pi*Ae)/λ²=(4*pi*f²*Ae)/c²
where Ae=effective area and f= carrier frequency. by the way if u want to increase the gain use wide band antenna like folded dipole and yagi in receiver. also as my knowledge say that u need only to increase the single strength so why dont u try to use wide band Folded dipole or Loop antenna especially circular loop.

the books for ur guidance i refer are
Refer to John D.Kraus J.Marhefta. Antennas for all Application. third edition full mathmatical explanation is given and whole project was made easy by this book.
Also THE ARRL Antenna Handbook: best book for antenna and application..

hope that it will help u

 

[Azulykit]

Re: antennas in parallel

When I am asked this kind of casual question I usually respond with the advice that if done "correctly" gain can be increased by around 3 dB. If done incorrectly it is very easy to reduce the gain by 30 dB. There is some improvement possible, along with a serious down side so proceed with some caution.

Murphy is alive an well, particularly in antennas.