Thoughts on VLF Earth-Mode and Induction DX

Earth-mode (through the ground conduction) and induction communication (mutually coupled coils) have an inverse cubed attenuation with distance. Think about this: I reached 0.3km with earth mode for an audible CW signal with around 4W RF and a simple 5m base receiver and 10m base transmitter. To double this range, all other things being equal, means increasing power by 18dB to 250W. To double range again means raising the power to kWs. Conversely, improving the detectable sensitivity threshold by 18dB (increasing the electrode spacings at each end, using WSPR or QRSS, etc) reduces in power needed for a given range dramatically: my 4W signal could be detected at 0.6kms or a just a 63mW signal could be detected by earth mode at 0.3km. In reality, especially in urban areas, water pipes and cabling may help "propagation" and achievable ranges may be greater. DX is relative, especially with conduction and induction at VLF.

Still being heard on 500kHz

This evening the reports on 500kHz WSPR have been quite reasonable, despite the smaller antenna than a few months ago. Three unique reports from PA and from the UK so far this evening.

Blog visitor DXCC

Just noticed that this blog has been visited by people from 102 different countries this year so far.

Another new WSPR report on 500kHz

Last night I got another new 500kHz WSPR report, this time from PA0O in the north of the Netherlands at 440kms. This brings the total of unique WSPR reports on the band (via the internet database) to 83 stations plus a couple of others who reported by email. Overall the total number of unique reports on 500kHz including CW is 86 stations in 11 countries. Not bad for 1mW ERP. The most recent reports have been with my "degraded" antenna consisting of the 5m feeder to my 28MHz halo as a top capacity hat.

W1VLF's page about 8.97kHz experiments

Paul W1VLF is getting operational on the 33kms band (8.97kHz) and has already been received 5kms away running 50W into a base loaded vertical. He has created a website to detail the progress as he goes along. At the moment the website only has details of his HUGE loading coil. See http://rescueelectronics.com/9-Kilohertz.html .

82nd unique 500kHz WSPR report

This evening I got a new unique WSPR report, the first in 3 weeks, from Chris G3XIZ. This is my 82nd on the band. Chris has just started on WSPR and is likely to come on WSPR TX shortly. He is a very experienced 500kHz CW operator.

Auroral Chorus Recording (Paul Nicholson)

If you missed the streamed natural VLF auroral chorus emissions the other morning here is a nice recording made by Paul Nicholson in Todmorden UK.  It is a truly unbelievable sound, produced not by birds but by the auroral electromagnetic activity at VLF.

Moonbounce from Aricibo

The Arecibo Observatory Amateur Radio Club KP4AOwill be putting the 1000-foot radio telescope on the air for 432 MHz EME from April 16-18. It can be heard with a small hand-held yagi pointed at the moon. A 15 dBi antenna and 100 W will be enough to work us on CW.

Times of operation are:

April 16: 1645 - 1930 UTC,
April 17: 1740 - 2020 UTC,
April 18: 1840 - 2125 UTC

Tx Frequency: 432.045 MHz,
Rx Frequency: 432.050 to 432.060+
Tx power: 400 W,
Antenna gain: 60 dBi

Antenna feeders

Today I have to move my two main antenna feeders which wind their way untidily through the house from the back of the house, where they enter the building, to my shack in a front bedroom. This means getting up into the small loft space to run the cables across and down. Some years ago I had a bent end fed antenna on 10m squeezed up there and it managed to get to South America on QRP SSB. A small ground plane for 10m (with a capacity top hat to shorten the vertical section) would probably perform quite effectively.

UPDATE: Job done. It took about 1 hour and everything is fine.

VLF Chorus audible in UK this morning

Auroral Chorus, a natural VLF emission that sounds like birdsong is audible in the UK this (early) morning. It is still audible at 0650z. Check out the VLF natural radio receiver at http://abelian.org/vlf/test.html as soon as possible, as it will soon be gone.