On 7/3/10 10:25 , Bob wrote:
Hello,

Enjoy sw listening, but frankly not all that sharp re antennas.

Over the past few months, I have seen several ads for those handheld sw
receivers and transceivers. From different mfgs.
About the size of the typical hand-held scanner receiver.

They all seem to cover up to at least 30 MHz, and most beyond.

Got to thinking about this a bit.
What do they use for an antenna for 30 MHz and below ?

I have a long end fed antenna for my listening.
Obviously they have a shosrt "something".

How effective is a short "something" around 5 to 10 MHz, e.g. ?

How can it work down there at all ?

Or, do they expect you to hook up something "decent" to it, even though
it is supposed to
be portable, and is very small ?

Any technical explanation on this would be mosgt appreciated.

Thanks,
Bob


Many SW portables do have adequate sensitivity to perform well
below 30 Mhz with the built-in whip, or a fairly short length of
wire. More than 20 feet on many can lead to overload issues on some
rigs.

But for handheld widebands, an longer antenna is needed. There
are many options available. I've seen and used whips of a meter or
more in length for HF on my R-10. A bit cumbersome, but not bad
performance. An external antenna that connects to the BNC mount on
the rig is useful for mobile monitoring. And some fixed base
operations.

For a while, Grove made a rubber ducky with an amplifier for HF
that works quite well on better handheld widebands, like those by
ICOM and AOR, Yupiteru and others. I have one and it's a nice
performer down to MW. No longer made, but the circuit is fairly
simple. It can easily be replicated.