On 7/26/2014 10:57 AM, amdx wrote:
On 7/26/2014 10:15 AM, Jeff Liebermann wrote:
On Sat, 26 Jul 2014 09:22:08 -0500, amdx wrote:
Hey Jeff,
Is it possible to build a tuned loop connected to the backside of the
radio, to cover the FM band. I never tried a loop at 100Mhz.
Mikek

Sure. Google for VHF magnetic loop antenna.
https://www.google.com/search?q=vhf+magnetic+loop+antenna&tbm=isch
They work so-so, but have the same problem as the HF version. The Q
is very high resulting in extremely narrow usable bandwidth. In order
to make it work, there would need to be some way of tuning the loop to
frequency. Making it track the receiver frequency would be a big
plus.

I expected to have a tuning cap on the loop to tune to his frequency
of interest. I don't know about polarization, but he may be able to
rotate out some interference with a loop.


Mikek


I've* calculated a 6 inch loop made with a #12 or #14 wire will
resonate the FM band with a cap between 6.5pf and 10pf. Roughly!
Now, I'll see if I can generate the gumption in the next couple
of days to build it to see if it has any positive effect.
I hope someone beats me to it.
With an AM loop and radio the signal couples to the internal loop very
well, I don't know how well you can couple a signal into an FM radio.
Mikek

* actually I used a couple of online calculators.

http://www.deephaven.co.uk/lc.html

http://www.daycounter.com/Calculator...lculator.phtml