| Firstly let's look at Gain
- If you look at the diagram below, with
the vertical line representing the antenna, the outer
circles indicates how the signal is transmitted with various
gain antennae. In summary the higher the gain the more
direct and pinpoint the signal, thus longer distance but
far less 'rollover' effect, consequently reducing performance
in hilly areas. |
|
|
| The diagram below typically shows what
happens to the signal between two vehicles - note how
the signal with a 3db gain antenna actually reaches the
second vehicle s antenna but the 6db does not |
|
|
Ideally if would be advantageous to change
antennas when in flat country and also when in hilly country
- This situation is certainly not ideal, so a compromise is
the only answer - In summary the best all-round choice is
4.5-6db
| Another question asked is - "What
does Ground Independent mean?" All antennas require
a ground plane to operate effectively. With UHF radio
Ground Plane is of utmost importance - The following diagrams
show how the signal is transmitted when the antenna is
mounted in various locations with either 'Non Ground Plane'
(NGP) antennae or 'Ground Independent' (GI) antennae -
Also note how the signal is polarised and not an even
360deg when the incorrect antennae is used |
| NGP-Bull bar Mount |
NGP-Side Guard
Mount
|
NGP-Centre Roof
Mount
|
GI-Bull Bar
Mount
|
|
