[600MRG] Ferrite antennas

[Warren K2ORS]

There are limits to the effective area of a ferrite loop which can be 
overcome with a large air-core loop. Ferrite increases the effective 
capture area of the antenna, but there are asymptotic limits. There are 
a number of papers on the subject with both theoretical and experimental 
results that back this up. If you want to do real DX you will need 
something better than a ferrite loop.

Ribbon cable is a poor choice for a multi-turn loop as the close 
proximity of the turns results in a high capacitance between turns and a 
limits the tuning range and Q. Ribbon cable is also made up of thin 
diameter wire which has a relatively high resistance (recall the skin 
effect at RF increases the effective resistance compared to DC), this 
further degrades the Q.

Almost anything will work to a degree, it's often the case that the ham 
with one antenna and nothing else to compare it to thinks that he has 
the best antenna in the world :-)


73 Warren K2ORS




On 2/15/2016 9:56 PM, J Mcvey wrote:
> Does it have to be ferrite based?One of the more innovative things I saw, was loop antenna made from some old (40 -50?? conductor) flat ribbon computer cable.He offset the end to end alignment by one conductor and soldered each wire end to end which resulted in a multi turn loop for VLF and MF . He said he used it with very good results. It was a diamond shape and about 3 or 4 foot  across if I can remember dimensions by just looking...
> Without lossy media, I think it would perform better , no?
>
>
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>      On Monday, February 15, 2016 12:11 PM, david vanhorn <kc6ete at gmail.com> wrote:
>
>
>   I am looking for a good reference on ferrite rod antennas.  Something like
> the ARRL antenna book but focused on ferrite antennas.
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> 600MRG mailing list
> 6

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