On Thu, 10 Feb 2005 21:44:43 +0000, Cynic
wrote:

On Thu, 10 Feb 2005 19:58:37 +0000, not available
wrote:

On Wed, 09 Feb 2005 21:53:17 +0000, Cynic
wrote:

On Wed, 9 Feb 2005 20:42:48 -0000, "Paul Nutteing"
wrote:

I thought aerial dimensions went to scale with the wavelength
I know an indoor FM radio aerial as a squashed loop is 5 foot long
Long wave aerials used to be the length of the garden
405 aerial was bigger than 625 aerial etc

Yes and no. *Some* aerial designs have to be a particular fraction of
the wavelength, but you will find that a LW and MW radio works just
fine with a 6 inch ferrite rod aerial instead of a 300 meter long
dipole.


Only partially correct. The Ferrite rod of the aerial is used to
concentrate the received field and link it to the coils wound on the
rod. The coils form a resonant circuit with the tuning capacitor. The
rod and coils combined are the arial and the rules regarding the
length of dipole aerials don't apply.

Quite, all stuff I learnt well over 30 years ago. So why do you say I
was only "partially" correct? Which part do you believe I got wrong?
A "ferrite rod aerial" describes the ferrite *and* the coil BTW.

You might also think about other things that are capable of
concentrating the received field.

OK point taken. It should be "only a partial answer"!

I was clarifying the point that Ferrite aerials can not be compared
with dipole based ones with regard to size. Paul may find it
interesting that some small AM receivers work well with a Ferrite slab
aerial just a few inches long.