On Sun, 07 Mar 2004 23:44:00 +0100, Jeppe wrote:

I am experimeting with 2.4 GHz pyramidal hornantennas like this one:

http://seattlewireless.net/index.cgi/CardboardHorn

But I ask myself: what is the optimal hight of the waveguide part?

Of course the hight of the waveguide has to be more than lambda/4 in
order for the lambda/4 antenna rod to fit in it. But how much bigger
should it be?

Jeppe

Hi Jeppe,

For the unbalanced probe, the throat cross section should show
1 by 0.5 wavelength dimension.
The mouth cross section should show
2 by 2 wavelengths.

The probe is situated on the face of the wider dimension, thus its tip
penetrates to the middle (where two diagonals would cross). The
illustrations are clear to this matter even though the dimensional
description is a bit rocky.

The standard gain of this antenna is 13dB (which is closely confirmed
by the author's measurements).

73's
Richard Clark, KB7QHC