View Single Post
  #1   Report Post  
Old June 2nd 05, 03:49 AM
Warren
 
Posts: n/a
Default Handheld GMRS/FRS radio antenna gain question

Hi everyone,

This sure seems like the group I've been looking for.

I've been researching GMRS/FRS handheld radios and have been a little
disappointed in the "bubble-pack" radios that are commonly available for
this radio band. The first thing I learned about was how ridiculous the
manufacturer's power ratings and claimed reception distances were. I've
decided to ignore the marketing & sales hype and just try to understand the
basic physics of radio.

The one thing I think I've learned is that three most important components
of a radio are the antenna, the antenna and the antenna. Most consumer
GMRS/FRS radios come with a three inch or less antenna but I've seen some
with a 1/4 wave antenna. My understanding is that FRS antennas can not
exceed the gain of a 1/2 wave dipole and they can not be interchangeable, so
you have to make the correct choice when you buy the radio. I have some
basic understanding of the general theory of antennas, and someone suggested
to me that a 1/4 wave antenna could suffer a 2dB signal loss compared to a
1/2 wave antenna. I'm interested in learning the additional dB loss in
going from a 1/4 wave to a 2-3" "bubble-pack" antenna.

I guess where I'm coming from is that I'm wondering if, all other things
being equal, can I realistically get equal or better reception with a pair
of 0.5 watt ERP radios with a 1/4 wave antenna versus a 1-2 watt ERP radio
with 2-3" antenna. The advantage of broadcasting with only 1/2 watt is very
desirable from a battery life point of view. I believe increasing the power
at the antenna from 1/2 watt to 1 watt or 2 watt gives me a 3 to 6 dB
increase in signal strength, respectively. If the 1/4 wave antenna on the
1/2 watt radio has a 3dB or better gain on both transmit & receive units,
due to better antenna design, I've achieved the same radio performance with
longer battery life, all other things being equal. I guess I'm asking if
there is any information that can help quantify the differences in the two
types of antenna design?