[time-nuts] Antenna

Poul-Henning Kamp phk at phk.freebsd.dk
Tue Jul 8 18:17:29 EDT 2014


In message <53BC56FC.3030909 at rubidium.dyndns.org>, Magnus Danielson writes:
>Hej Poul-Henning,
>
>On 07/08/2014 09:59 PM, Poul-Henning Kamp wrote:
>> In message <53BC4B9F.6040302 at rubidium.dyndns.org>, Magnus Danielson writes:
>>
>>> I have a FS700 sitting here, but no antenna. There should be other
>>> signals than LORAN-C/CHAYKA available, such as DCF77, MSF60 and the 162
>>> kHz signal from outside Paris. It would be pretty straight-forward to
>>> put up a frame and make a number of turns of wire, and put a low-noise
>>> amplifier up in the attic. What existing projects should I look at or
>>> take inspiration from?
>>
>> http://phk.freebsd.dk/loran-c/Antenna/
>
>What is your loading on the coil? How many turns? Schematic?

No loading, I wanted flat frequency response.

No ideas how many turns, it's not critical.

>Cooking up a low-noise amplifier for these frequencies seems relatively 
>simple, but it is always nice to see what others have done.

I just winged it, I looked at the stuff at VLF.IT then the AD797
data sheet and when it worked well enough I stopped.

I have also built a "monopole" antenna, based on the schematic on page 6
in this article by Chris Trask:

	http://home.earthlink.net/~christrask/Complementary%20Push-Pull%20Amplifiers.pdf

The performance is astonishing: it pulls in everything from the
Schumann resonances and ~10kHz russian "Omega-like" naviagation to
100 MHz FM radio, but also every source of noise you can imagine
in your neighborhood.

In difference from the loop which needs none, this antenna needs a
really good earthing.


-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.



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