[160m] 160m Digest, Vol 56, Issue 1

[David Cutter]

I've seen 2 designs for ferrite rod rx antennas made in completely the 
opposite style: one had several rods glued end to end with an LC tuned 
circuit in the middle all mounted in a plastic water pipe for external use 
and one in which all the rods are bundled together and mounted on a wood 
base for indoor use.  I've often thought about making them to compare.  I 
must try to locate those articles, but each claimed that it was the nulling 
effect that gave the advantage, to point at a seriously offending station or 
source of noise.

David
G3UNA


>  I was thinking last night as i was listening to coast to coast on my
> AM radio.
>
> The question is,  While i know for sure we could not use it for
> transmitting,  But the ferrite bar antenna that is inside this radio,
> How efficient are these anyway?  I know they are highly directional,
> with very deep nulls.  But has anyone ever made one for use on 160 meters?
>
> And if so what did it perform like?
>
> The directionality would be nice. how about noise, or overall gain  etc?
>
> Joe WB9SBD
> -- 
>
> The Original Rolling Ball Clock
> Idle Tyme
> Idle-Tyme.com
> http://www.idle-tyme.com
>
>
> ------------------------------>
> Good thinking. The small rod antenna has an overall pattern much like a
> small loop antenna. The rod length direction is like the axis of the small
> loop antenna, and would be the direction of nulls.
>
> Unfortunately the are not highly directional, they are the opposite! The
> pattern has very narrow very deep nulls, but in all other directions it 
> has
> strong response. This means the directivity is not good, only the nulls 
> are
> sharp and deep.
>
> It would be good for nulling noise or unwanted signals from a small 
> specific
> area, but not much good if noise comes from multiple directions.
>
> Efficiency is very low, very small fractions of one percent. This doesn't
> matter much for receiving, but it does for transmitting!
>
> 73 Tom
>