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Re: LF: RE: 8.9758KHz Earth Mode Test 21st Dec.

To: [email protected]
Subject: Re: LF: RE: 8.9758KHz Earth Mode Test 21st Dec.
From: g3zjo <[email protected]>
Date: Sat, 21 Dec 2013 10:29:09 +0000
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HI Jim

FWD from G3MFW

Thanks for your interest, you obviously know much more about it than I do! I would be interested to study your results. I will look out for broadening of my signal when I try narrow bandwidths, but nothing is apparent at 1.46Hz. I am sure I am not losing any current to undesired paths. I have wired the system with mains wire (3 conductors in parallel), 2 inches above the ground. I measured the resistance at 8.97kHz from the house pipes to each earth individually. They ranged from 159 to 490 ohms, the calculated parallel resistance being 22.4 ohms. However, when connected together they measured 33 ohms. I am not expecting a miracle with my test, but with VLF you never know!
Harry, G3MFW


Eddie

On 19/12/2013 18:54, hvanesce wrote:

I am out of range (Arizona this weekend) for your experiment, but interested. I have carefully measured infrastructure effects (including buried utilities and other utilities), and have coincidentally seen roughly 6km range (at VLF frequencies) in a scenario that is somewhat similar. For what it’s worth I found steep field gradients near 3km-6km (infrastructure and topology dependent) in four directions, and did not have time or RX dynamic range to determine whether these gradients were associated with multi-modal interference nulls, utility decouplers, or simply extinction of the reactive field. I hope to extend my RX dynamic range by ~ 20dB in the near future, and will repeat these measurements (at ranges > 6km) at that time.

 

Does your infrastructure broaden your signal and/or add spurs? I suppose you can’t know this until your test is underway, but it might be helpful for others to eventually know this, on the chance that some infrastructure resonating off center frequency has a large aperture and could therefore be detected more easily than the fundamental at ranges > 6km*.

 

At 50V, 1.5A  (~ 33 ohms) do you think that you are losing any current  to undesired paths?

 

Best of luck on your tests.

 

73, Jim AA5BW

 

*  (given your antenna contact separation, it seemed that infrastructure aperture might be significant compared to coupling between your earth loop and the infrastructure, for RX separations > 6km, at which distance the reactive field may be giving way to aperture-dependent quasi-static and radiative field components)

 

From: [email protected] [mailto:[email protected]] On Behalf Of g3zjo
Sent: Thursday, December 19, 2013 10:01 AM
To: [email protected]
Subject: LF: 8.9758KHz Earth Mode Test 21st Dec.

 

G3MFW has problems posting to the Groups at the moment, I have received the following from him.


I have been experimenting with earth systems for some years. I now use the house water pipes and an array of 11 copper earth rods and buried sheet in parallel, 30 metres away at the bottom of the garden. At 8.9758 (crystal) I pass 1.5 amps at 50 volts RMS. I have made a reception map around Truro, Cornwall, at 1.46Hz bandwidth using a 41 turn horizontal loop on the car roof rack, supplemented by using the same loop on the ground. Ranges vary greatly with topography and earth conditions, but are up to 6 Km with buried utilities assistance.

I will transmit this Saturday, 21st Dec, from 9.00 to 10.15 am using QRSS 3 with endless dashes. I would be most grateful if you would report any reception using narrow bandwidths. I must be exciting several square kilometres of buried utilities – surely SOMETHING must be radiated! I can repeat the test at any time upon request.

 

Harry Woodhouse, G3MFW




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