Loggings > Longwave Loggings

Receiving LWBC in North America

<< < (3/3)

pinto vortando:
Have never had much luck with LWBC here in the upper Midwest... can sometimes hear something on frequency
but cannot seem to "pull it in".  My antenna is obviously not up to the task. 

MojaveBeaconeer:
171 Medi-1 seems to now be inaudible "out west" here in CA compared to the early 2000s to about 2010 - I think this is because they went to a directional pattern that nulls North America - . Once quite easy in Inyo Co. CA to hear after evening dusk in the winter when the K-index was ZERO (and I caught them loudly in western AZ April 2009 with just a random wire atop some Saguaros). This before they went to the NA-semi-null.

The best antenna for LWBC and LW in-general is a good directional BEVERAGE antenna (look that one up).  You will get a lot more help with LWBC reception at the LWCA site and IRCA/NRC (the principle North American DX clubs). "Beverage on ground" wires (i.e. - simply spool out 300m/1000 feet on the ground or atop shrubs/etc. in-lieu of those 3m tall (plus) poles will offer amazingly directional reception - these are called "BOGs" and DXers employ them with amazing results!  "Terminate" the far-end of the wire to a ground rod 1m meter deep if possible (alternatively attaching the far end to another spool of wire and just putting the spool onto a ground rod or even wrapping it in a plastic bag and burying it just under the soil surface works to reject signal reflection from the far-end thusly reducing the undesired "back-lobe" ( most BOGs do not really need that 200-400 ohm resistor in-series to the earthing-rod - I find - as earth grounding is rarely low enough resistance with a single earthing rod). As such, this all makes the wire quite unidirectional toward the axis of direction of the wire. 

BOGs have a cool phenomenon pertaining to a "velocity-lag" of the signal in the wire vs. light-speed, and this further pulls the reception pattern into the reception-lobe along the axis of the wire.

For amazing receptions of LWBC stations via Bevs, listen to samples here:

https://archive.org/details/TheBestOfHawaiiMediumwaveamBroadcast-bandDx-86To91

AND:

https://archive.org/details/KeelerFenceBeverage1

For the time being - "forget about it" now, as storm static noise (QRN) and now a rising solar-max and huge attenuation of LW signal DX now (including NDBs) has now ensued - it is now like a -20 dB suck-down of LF signal strengths has ensued - just since the January 2022...

Solar-Minimum periods (such as between 2016 to as recent as October 2021) were the BEST epoch for long-haul LWBC DX, but it's all going away and the LWBC signals are rapidly leaving the air, too (alas!). 

Brave New World... 73MB

circuitmike:
Thanks for the good info! I'm familiar with beverage antennas and I'd love to set one up, but I just don't have the real estate for that on my quarter-acre lot. I hadn't heard of beverage-on-ground antennas, though - that's interesting. Maybe one day I'll live somewhere with the room to set up something like that.

I don't know as much about propagation as I'd like to, so I had no idea that the solar minimums were actually good for LW propagation. I wonder how many LWBC stations will even be left when the next one rolls around. I do some casual NDB listening and I've logged a bunch of them from Quebec and Ontario but never anything I'd really call awesome DX. But I've done all that with my Wellbrook loop, which is great, but I realize it's no beverage.

The rising QRN is really frustrating, as is locally-generated noise.

Helen:
Dear circuit Mike

You were asking about  a suitable ant for low frequency.   Firstly  a simple loop antenna  a few turns of insulated wire on a simple frame made of wood.
is simple and very cheap. It is also practical.  and will out perform any of the long wire Antennas previously described since the Antennas suggested are ment to be several wave lengths long. The beverage is a great receiving antenna if you have half a mile or more of space and can pay for the copper.

If you look at old books from the 1930s you can see radios advertised with a 10 inch loop in the back. They were the standard for long and medium wave radios. with the desired move to smaller radios loops were modified to use a ferrite core making the antenna smaller with out loosing to much performance.
The length for a halfwave dipole  is  the speed of light devide by the frequency that gives you the wave length. The half wave length is the wave length
devided by two.  300,000.000 / 180  = 1666   div 2   =833 meters  multiply that by ten for the long wire antennas and that is a lot of real-estate.

Look around the technical web page that engineers and radio hams use. they have some really good ideas. And experiment.   Making good antennas for low frequency has almost become a forgotten art.
Kind regards
Helen
.
Loops work very well. you can make one for two 200khz  by using 30 40 turns and a tuning capacitor. 
Or you can make a bigger loop maybe 4 ft square you need less turns.   
Look up ham radio web sites or even Wikipedia  will give you more information.  The big advantage the loop is directional so by pointing it carfully you can make the signal you want stronger and reduce interference.  In the country be for FM became popular a lot of people used loops. If you are interested in Radio join a local Ham radio club.  Checkout Wiki maybe by the ARRL hand book or similar.  Where I live they are closing a lot of the beacons.  The Marine Band has been closed for years now.  But there nis still a lot of stuff around.  Good luck.

Pigmeat:
Good advice, Helen. I got most of my SW tropical band dx catches with a design for a MW loop from Radio Nederlands that I accidentally cut the frame too small. It worked well from the 120 meter ham band through the N.A. pirate band, indoors, sitting on a table. Once you got the right heading, it was a matter of tweaking the knob on the capacitor.

Believe it or not, some pirates lied about where they were tx'ing from. Shocking!

Navigation

[0] Message Index

[*] Previous page