Antenna for LW

Useful information regarding antennas for SDR products.
illllm
Posts: 56
Joined: Wed Jan 23, 2019 10:26 pm

Antenna for LW

Postby illllm » Mon Jan 28, 2019 3:19 am

For someone living in a small space, what would be the best way to receive LW? Would it help if 500 feet wire was coiled? Or zigzag?

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Mike2459
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Joined: Mon Jul 24, 2017 8:24 pm

Re: Antenna for LW

Postby Mike2459 » Mon Jan 28, 2019 3:30 am

I have had good luck with a mini-whip hanging from a tree 11 feet above ground level. A good wideband mag loop antenna would be even better. Much depends on your background noise levels. Better hurry, long wave season will end soon.

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g1hbe
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Location: Cheshire, UK

Re: Antenna for LW

Postby g1hbe » Mon Jan 28, 2019 9:14 am

My LW/LF listening is spoiled by high noise levels from local gadgets, and the only cure was to get a loop. I use the Wellbrook 1530 but there are other types. If you are handy you can make your own using the well-known PA1M circuit. If you want it to go down to VLF, use a mix 73 ferrite transformer as the common type 43 falls off below 100 kHz.

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Andy

franko
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Joined: Mon Aug 28, 2017 9:33 pm

Re: Antenna for LW

Postby franko » Tue Jan 29, 2019 6:51 am

Mike2459 wrote:Better hurry, long wave season will end soon.

Can you say anything more about what you hear, and when during the year you hear it?

I'm unable to hear anything on LW due to very strong local MW broadcast interference, but am in the process of obtaining a low-pass filter. Interested in what might be out there to listen for. (Southern California in my case.)

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Mike2459
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Joined: Mon Jul 24, 2017 8:24 pm

Re: Antenna for LW

Postby Mike2459 » Tue Jan 29, 2019 5:15 pm

Overwhelmingly NDB's (Non directional beacons).

You can investigate for yourself with the Maritime Radio Historical Society's low band KIwi SDR at http://198.40.45.23:8072/
It is connected to a Marconit T antenna.
I could only find 4 active NDB's in California in the ClassAxe database.

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franko
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Joined: Mon Aug 28, 2017 9:33 pm

Re: Antenna for LW

Postby franko » Tue Jan 29, 2019 5:24 pm

Mike2459 wrote:Overwhelmingly NDB's (Non directional beacons).

You can investigate for yourself with the Maritime Radio Historical Society's low band KIwi SDR at http://198.40.45.23:8072/
It is connected to a Marconit T antenna.
I could only find 4 active NDB's in California in the ClassAxe database.

Thanks, I'll check them out.

I've heard that WSPR is fairly popular on the 630m and 2200m ham bands, and thought I'd also set up WSJT-X to see if I can pick any of that up.

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Mike2459
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Joined: Mon Jul 24, 2017 8:24 pm

Re: Antenna for LW

Postby Mike2459 » Thu Jan 31, 2019 7:48 pm

Can you say anything more about what you hear, and when during the year you hear it?


Sorry, I didn't fully answer your question. Anytime thunderstorm activity is low. late summer, autumn and winter seem to be the best here in the eastern US. The QRN from lightning activity can travel great distances at longwave frequencies.

You mentioned WSPR in your last post. I tried it out last light, heard several hams in Arizona and New Mexico on 630 meters. There was one log entry for K9FD in grid square BL11 (the Hawaiian Islands).

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franko
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Joined: Mon Aug 28, 2017 9:33 pm

Re: Antenna for LW

Postby franko » Thu Jan 31, 2019 8:05 pm

Mike2459 wrote:Anytime thunderstorm activity is low. late summer, autumn and winter seem to be the best here in the eastern US. The QRN from lightning activity can travel great distances at longwave frequencies.

You mentioned WSPR in your last post. I tried it out last light, heard several hams in Arizona and New Mexico on 630 meters. There was one log entry for K9FD in grid square BL11 (the Hawaiian Islands).

Lightning is pretty unusual here in Southern California, though ironically we're having a very rare day of thunder/lightning storms today.

I ordered a low-pass filter (to attenuate MW AM broadcast) from Par Electronics, and will look forward to trying it out when it arrives (expected Saturday).

Thanks for the mention of the ClassAxe database -- that looks like it will be a useful resource.

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Mike2459
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Joined: Mon Jul 24, 2017 8:24 pm

Re: Antenna for LW

Postby Mike2459 » Thu Jan 31, 2019 9:50 pm

I see what you're talking about:
SoCal.JPG
SoCal.JPG (46.99 KiB) Viewed 3243 times


I can hear these at 30KHz in my area:
Gulf Coast.JPG
Gulf Coast.JPG (65.17 KiB) Viewed 3243 times

https://www.lightningmaps.org

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franko
Posts: 55
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Re: Antenna for LW

Postby franko » Fri Feb 01, 2019 7:19 pm

Great lightning map website!

Mike2459 wrote:You mentioned WSPR in your last post. I tried it out last light, heard several hams in Arizona and New Mexico on 630 meters. There was one log entry for K9FD in grid square BL11 (the Hawaiian Islands).


In addition to WSPR, it seems as though there's a certain amount of JT9 traffic, more so on 630m but also 2200m. Here's a map of spots from PSK Reporter:

JT9-475kHz.jpg
JT9-475kHz.jpg (155.47 KiB) Viewed 3204 times

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