Increasing to -14 dbm seems to help reception problems.

[badjef]

I do a LOT better than that when I visit Minneapolis, well over 100 miles - maybe 120. Granted that is a Pioneer Supertuner 3D, but still. Maybe - it has something to do with car antennas. Somebody decided 31 inch whips didn't look "cool" and now we only have cute little nubs or elements hidden in windshields. Which equals LOUSY reception. Too bad that movement in cars coincided roughly with the introduction of HD radio. HD could have really benefitted from those whip antennas.

I recognize there's no substitute for the bigger antenna on the fender but I've seen some good results from stubby antennas if they are coupled with a good amplifier. The one in my car (which has since corroded and quit working) did fantastically well for such a small piece of metal, but even it's foot+ length is much bigger than the shark fins I see a lot of newer cars sporting.

I can only imagine the complexity of pairing something like that with a second antenna in the
windshield (a la "Diversity Antenna" in old Nissans) with HD.

And thanks to everyone for the dB discussion; it helps put things in perspective.

An amplifier that works rather well is made by Bosch.it is used on Van Hooligan Motorcoaches which is where I had experience with them and they are also on the other European cars as well.

But one must understand an amplifier amplifies noise as well. It must have some signal to help the radio's front end. Once it gives enough signal for the radio, then the front end will grab it and the radio tune to it. If there is not enough signal for the front end, the radio will amplify noise until the signal reaches that level.

An antenna, properly tuned to the frequency and length, will grab much less of the signal more effectively.

Jeff in Sa-ra-so-ta!

 

[SirRoxalot]

Just to add to the dB discussion...

The rule of thumb on dB is that a 3 dB increase doubles the power, and a 3 dB loss halves the power. A 10 dB increase gives you 10x the power, and a 10 dB loss cuts you to 1/10 of the power. All of these are cumulative. So...

+3 dB doubles the power
+6 dB doubles it again - so you have 4x the original power
+9 dB doubles it a 3rd time - giving you 8x the original power
+10 dB gives you 10x the original power
+13 dB give you 10x the original power, then doubles it to 20x the original power
+16 dB would give you 40x the original power
+20 dB would give you 100x the original power

-3 dB halves the power
-6 dB halves it again, to give you 1/4 of the power
-9 dB halves it again, to give you 1/8 of the power
-10 dB gives you 1/10 of the power
-13 dB gives you 1/10 of the power, divided again by 2, so you have 1/20 of the power
-16 dB divides it again by 2, giving you 1/40 of the power
-20 dB divides your original power by 1/10 of 1/10, yielding 1/100th of the original power

The actual formula for dB is dB = 10 log P2 (output) / P1 (input). The "rule of thumb" is close enough for most applications.