Nigel Molesworth wrote:
On Wed, 31 Dec 2008 14:16:57 +0000, Dave wrote:
You have not stated the frequencies you need this for.
Is there more than one VHF FM broadcast band then? I guess 88MHz to 108MHz.
I don't think I've made my problem clear: I don't have space to mount a 1.5m
antenna, hence my OP "Modern cars seem to have much shorter aerials ..."
I've got about 75cm of headroom, so I need to use a short antenna, like they
have on cars. So how are they made to be short?
The whip(s) on my FM receiver(s) seem(s) to demonstrate a complete
disregard for polarization, lay it horizontal, it works well, stand it
up vertically--it works well, sometimes a positive change in signal can
be had, sometimes not, sometimes an improvement--sometimes not. I have
not done a thorough study, but it all seems completely random, location,
nearby metal objects, structures, etc., most likely, contribute to all
this, also ... but, I hazard to guess, that quite often, polarization
gets "screwed" up on the way to the receiving antenna.
Currently, I have a 1/2 wave DLM (distributed load monopole -- Robert
Vincent) up in the attic which provides input to a homemade preamp
utilizing a MMIC device. Most of the time, the preamp is not used ...
however, I do kick it in because, I am in a poor location to receive NPR
and it makes the difference in being able to receive a low power, local
college station satisfactorily.
Of all the antennas I have tried, this just simply works the most
satisfactorily for me. It would be possible to construct the DLM in a
dipole configuration and run it horizontal, but, like I stated, I just
don't have all that much faith in that paying all that much attention to
polarization, at FM broadcast freqs, will provide a great benefit(s.)
And, of course, others' mileage may vary ...
But, for a cheap quick fix, the folded dipole, already suggested, helps.
Regards,
JS