Hi all

I am gradually working up to a project to TX telemetry from the car at
very low QRSS type data rates. Because of the unattended nature of the
system I am going to start using the HiFER freq of 13.56Mhz rather than
a "real" amateur allocation.

This of course means very low output power and no doubt a number of
other limitations for the TX. I really only need the system to work
predominately 10 miles from the base.

Yes I am aware of the frequency stability issues for very narrow band
signals. No doubt the vehicle bouncing around wont help either! May end
up using a Picollo type system where the freq difference between two
states is used to send data.

I am after some feedback and ideas about antenna systems to use. I
suspect the car TX antenna will only be a wire draped across the rear
window or a loaded broadcast antenna. The RX base antenna was going to
be just a dipole but I reasoned that this would be great for DX but
terrible for groundwave. Then thought about a vertical dipole, but am
concerned about the higher noise level. I'll probably end up trying
both. Initial tests are only going to be looking for a CW signal on a
waterfall.

Would also consider experimenting at a MedFER freq around 1700KHz but
base antenna efficiency might be pretty bad. There is also a lot more
RFI there.

Ideas welcome. If however you want to say it "wont work" please back it
up with some maths/calcs or your own direct experiences.

Cheers

Bob VK2YQA