FYI, Everyone has seen the full spherical radiation pattern of a dipole and the
hemisphere pattern of a 1/4 wave over groundplane with an additional 3 dB
gain Bit it is not valid in most cases.
No matter how you mount the antenna to its "ground plane" it will not
have a hemisphere pattern unless the ground plane is an INFINITE sheet
of metal in all directions. Similarly it wont have the added 3 dB
gain either.
The radials or metal of the small vehicle will in fact, lend to a
match to the coax, but it does little to the antenna pattern. At any
distance from a raised radial ground plane antenna, it will still be
an omni pattern. The radials, etc only help provide a match. Of
course on a car or s omethign approaching the size of a wavelength,
then there will be a pattern developed. But not due to radials on a
raised "ground plane" antenna.
Just sayin.
Bob,wb4apr
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On Sat, Sep 18, 2021 at 11:23 AM Allen Lord <allen@...> wrote:
Do you mean a 1/4 whip with four or more 45 degree radiators when you refer to a "Ground Plane" antenna? Or a quarter wave whip mounted to the bike's chassis?
73,
Allen AF6OF
On Fri, Sep 17, 2021 at 6:57 PM <toy4trax@...> wrote:
Allen,
I'd have the MTT4BT in a pelican type case, similar to the AIO. If the AIO would have been transmit and receive, GSA, GSV, that would have been a good combo... but alas, no.
Anyway, my goal was to take the GSA, GSV to/from my Garmin for GPS and display of the APRS waypoints. All this works on the bench.
So, MTT4BT in pelican case, bulkhead connectors out to Power/data, antenna.
Got the 8 watt so the ground-plane would not be an issue on an ATV/Moto(?). Maybe I'm wrong with this?
