Re: Loop height above gnd and 2 loops


Chris Moulding
 

Hi Simon,

I plotted the antenna pattern today.

I used a strong medium wave station in ground wave range as a source and turned the antenna making signal measurements every 20 degrees.

Results on 160m will be similar only with slightly reduced levels in the nulls.

The unsymmetrical "lump" in the pattern was caused when the antenna was pointing directly at the reflection off the metal clad school building next door about 20m away.

The -3 dB beamwidth is 100 degrees.

On the attached chart the inner circle is the -20 dB ring.

In the design the resistor caused the loop to operate as it's own sense antenna but as the sense antenna works as a vertical it needs some form of earth or counterpoise. It doesn't need much as the earth rod I used was only pushed 6" into the soil so it's possible that say a 1 m length of wire hanging down will also act as a counterpoise. I'll test that tomorrow.

Regarding your comment on a Beverage antenna, I did some work on Beverage antennas a couple of years ago as I was commissioned to build antenna amplifiers for a major European contest group. I searched the internet for Beverage's original articles and found his original report to the A.I.R.E which details all his work after the patent was granted. A lot of the stuff written by amateurs about Beverage antennas is incorrect and they can be used at HF as long as the length is kept to a maximum of 2.5 wavelengths.

I did a demo at the Bolton Wireless Club where we ran 40m of wire out along the car park. It happened to be in direct line with Moscow and we spent the evening listening to radio amateurs on 80m around Moscow coming in like locals!

I've posted all the articles on a web page:

http://www.crosscountrywireless.net/beverage_antenna_amplifier.htm

Regards,

Chris


On 10/11/2020 18:11, Simon wrote:

[Edited Message Follows]

Hi Chris

did you have any time today to do measurements?

also..been thinking..( a bad thing maybe.)..if the directional  loop can not null out the smpsu noise here in the direction i want the antenna to face ( most of the time.) ie nw to usa, then a phasing unit with another standard loop picking up the noise..cancelling out.??? .though i can see this upsetting the radiation pattern abit..

also the earth on the new loop vertical sense wire..what type of earth? A rod in the gnd..or tied to existing radial system etc..
due to my location, the earth could be a long way from loop..( unless mounted on side of house.) even this if on side  I expect will cause issues..6 m vertical wire with 2 m horizontal at best..no way here of having the loop above gutter height and a direct gnd..
electical noise pickup from the earth..will it not make the loop “noisey”??

how about if vertical length at 6+2 is ok combining your neat recent isolated earth solution ( rad com.) 

is there a min or max length of sense wire?? Itching to try it..but to start with would be only 2-3m above gnd..( test.)

Sorry for the questions..simon

(of course all of above would be irrelevant if someone on here in the sticks would offer me use of their field to put up a beverage and use their wifi..happy to rent....lol.)
-- 
Chris Moulding
Cross Country Wireless
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