[Lowfer] A little lower than lowfer...

[Ed Phillips]

w0ah@a-1st.net wrote:
> 
> Hi Kurt,
>   That would be a great dish for 18 GHz!  I use a 2' dish for 10 GHz. I
> don't think it would work on 18 KHz, but I know some of my fellow birders
> use similar size dishes for listening to bird songs at a distance so
> maybe?  Can anyone explain why a 2' dish will not even work well at 50
> Mhz, but does provide gain at the audio frequencies?
> Doug W0AH

	The dish in question is reflecting acoustic waves, not radio waves. 
The velocity of sound is around 1100 feet/second and the velocity of
light is about 983,500,000 feet/second.  The wavelength is the velocity
over the frequency and the wavelength is of the order of the
wavelength/diameter radians in the same system of units.  So, the
wavelength of sound at 18 kHz is less than that of RF at 10 GHz.

Ed