With the UHF aerials they don't need a ground plane to transmit. The old 27 mhz ones did-uhf don't-just mount it on the edge of the roof rack and it will roar to life. They are like any transmit aerial-the higher the better-just watch out for car park roof limits.
Jaros
I dunno about that Jaros. A ground plane is the antennas earth or means of controlling current.. you need something to maintain current control, without it everything goes heywire. Be interesting to see what disconnecting an antennas earth does compared to using it, compare the antenna's VSWR and resonance, my bet is you'd see a shift in both not to mention feed point impedance & a shift from current to voltage feeding or visa versa. This can then induce a multitude of problems!
If you remove earth on a 1/2 wave dipole you've now a 1/4 wave.. amongst other things you see a shift from 50 down to 25 ohm input impedance.
An antenna is nothing more than a tank circuit. A lot of mobile antennas have an integral components and along with the antennas parasitic elements, this creates the tank circuit. In the below photo the person has introduced integral capacitance and inductance to complete the required tank circuit tuning.. tuning for the desired operating frequency. If the person removed earth on this antenna, they have nothing but an end fed vertical long wire.. input impedance would go from 50 ohm to probably up around 1000 or even more. Radiation pattern would change, resonance would change.. everything changes
99.9% of radios, be handheld or otherwise are 50ohm input. So, you need to feed the antenna at a 50 ohm point. On a 1/2 wave dipole the 50 ohm point is mid way along the 1/2 wave length, this just so happens to be the dipoles low current point too. Shift the feed point and now you're voltage feeding and outside the zero current point, feedpoint resistance goes up or down from 50 ohm... a mismatch.
Phased array antennas are all about manipulating opposing currents, you can't do this without using the antennas negative side, its impossible. The same can be said for any antenna, you cant control current when there's no negative, actually you can on long wires but thats a little more complex. If you do remove negative on an antenna, theretically your now end feeding... amongst other things Z goes birsirk! So simply omitting earth may very well be changing the tank circuit tuning, be parasitic or otherwise, doing so in an unconfirmed manner aint good.
When you dont know the tank circuit and or antenna design, the only sure way of telling if removing earth is changing anything is to comparatively test the scenario on a VNA. A cheap eBay VNA made in Cheyna would suffice.
Myself, amongst other reasons beyond the antenna design, I always use earth for safety reasons - lightning!
Thuraya also known to be a much clearer natural sound also than Iridium phones. Characteristic of the different phones apparently ?. Iridium only $16.50 a month also, pay for calls out only.
