Batboard

I know that you need the right antenna on a mobile radio. Do you need that in a portable also? I know there are UHF, VHF, and 800 MHZ antennas and that the right one is needed. But, what happens if you don't have an antenna? Will a VHF antenna work with a UHF radio? While I am at it, why is there different antennas for different bands. Why won't they work on just one antenna?

They won't radiate the RF properly, so it will go back into the radio and probably end up burning the RF circuitry, and radiating from the antenna as heat.

If you don't use the right connector/antenna type, the RF may not even make it to the antenna, and will just radiate right from inside the guts.

Either way, it's bad news. It won't happen instantly, and probably won't happen over a short period of time, but it will happen eventually.

if it's recieve only then take your best shot but to transmit the length of the antennae has to be tuned to the band and some gain antennaes get tuned even more down to the frequency. but like stated earlier, it WILL burn up the transmitter if it's wrong. the same thing goes for mobiles and portables.

It's the same reason there are different length strings on a guitar or other instrument. Wavelength is inverse to frequency. So, higher frequencies need shorter antennas and vice versa.

You don't make high pitched tones on a bass guitar just as you don't try to make a 39 Mhz lowband antenna resonant at 800 Mhz.

motofreak008 wrote:...............While I am at it, why is there different antennas for different bands. Why won't they work on just one antenna?

You can play high notes on a bass guitar. Ever heard of a pinch harmonic? It's tougher to play on bass than a standard electric guitar, and it's much quieter, but it can be done.

Just like how a lowband radio can emit spurs on 800MHz

I had a UHF radio that was in the 450's that would open up my scanner on 46.44, and you could hear the person talking on the 450 freq in the scanner a good amount away so was not front end overload, its interesting how that works

You were probably listening to an IF in the transmitter.

Alllright.... but it was the simplest analogy I could think of at the time.

ke4zdg wrote:You can play high notes on a bass guitar. Ever heard of a pinch harmonic? It's tougher to play on bass than a standard electric guitar, and it's much quieter, but it can be done.

While everyone can agree that transmitting into an antenna on the wrong band is really bad, I wanted to offer some perhaps unconventional experience on receive.

I don't have an antenna for my VHF HT yet, so, when I use it (receive-only), I put on the UHF stubby from another radio. I started using it in a pinch, expecting poor results. Much to my surprise, it worked great, about on par with my other VHF rigs.

Of course it'd be better to use the right antenna, but, for receive, I get decent performance with the wrong antenna. (Just remember not to transmit!)

That explains a lot. The guitar analogy made a lot of sense to me. I never thought of that. Thanks for all of the input guys!