RSGB RadCom article on low noise vertical antennas with loop counterpoises


Chris Moulding
 

Recently we had a discussion about an antenna design I had published in the RSGB (Radio Society of Great Britain) RadCom magazine.

I've now received a PDF file of the published article from the Technical Editor and it can now be shared online.

Please note that the RSGB retains copyright of the article and it is used with permission of the RSGB.

The link to it is: www.crosscountrywireless.net/202010 loop counterpoises.pdf

Regards,

Chris


Paul Sayer
 

Thanks Chris. I could make this, but I don't see how a loop on the ground replaces multiple ground radials. Certainly in respect to efficient Tx.

Am I missing something? All references to efficient ground mounted verticals rely on many radials or a ground screen. Not a loop.

Regards, 

Paul G0VKT 

On Wed, 21 Oct 2020, 17:13 Chris Moulding, <chrism@...> wrote:
Recently we had a discussion about an antenna design I had published in the RSGB (Radio Society of Great Britain) RadCom magazine.

I've now received a PDF file of the published article from the Technical Editor and it can now be shared online.

Please note that the RSGB retains copyright of the article and it is used with permission of the RSGB.

The link to it is: www.crosscountrywireless.net/202010 loop counterpoises.pdf

Regards,

Chris


Chris Moulding
 

Paul,

A few  points to consider...

I only have a very small area available for radials or counterpoises. My back yard is 7/5 x 2.5m (22.5 x 7.5 feet) with a similar area on the track at the back of the house so it's not possible to make an efficient radial field. Each loop acts as a very wide radial.

I proved that having radials close to nearby electrical wiring picked up RF noise by capacitive coupling from the end of the radial. Using isolated loop counterpoises with an isolation transformer reduced noise levels to near rural levels even so close to the house.

After publishing the article I've had a lot of feedback from RSGB members who have built and tried the design with good results in reducing local noise pickup. Several have already found that it's best to make a four loop system in a configuration like the petals of a flower.

Regarding transmit efficiency it certainly works OK for me even on 160m but then I don't have a field with 120 radials to compare it with.

If we stuck slavishly to published reference designs we would not discover anything new.

Regards,

Chris


Paul Sayer
 

Hi Chris,

Many thanks for your reply.

My setup is in a mobile home that is made of steel and aluminium. Flagpoles at either end support and inverted L. The other half of the antenna is the van.  Until recently I couldn't get a load below 80m. But now I can get to 160m after a few changes. 

I am on heavy clay that is now going from concrete hardness to mush. A good time to try a loop on the ground that can be just below the surface so my neighbours don't trip on it and the tractor mower doesn't eat it! Been wanting to try one. If I positioned it near to the base of the driven flagpole I could try it out as a counterpoise. Wouldn't be hard to isolate the antenna from the "van" ground. Nor would it be hard to compare Tx performance using the counterpoise only or the "van" ground.

I agree, experimenting is fun and a learning experience. What I lack is time more than anything.

Regards,

Paul.


Kenneth Tucker <kenneth.tucker41@...>
 

Sorry, I'm not Chris

Kenneth R. Tucker


On Friday, October 23, 2020, 07:31:44 AM EDT, Paul Sayer <paulsayer123@...> wrote:


Hi Chris,

Many thanks for your reply.

My setup is in a mobile home that is made of steel and aluminium. Flagpoles at either end support and inverted L. The other half of the antenna is the van.  Until recently I couldn't get a load below 80m. But now I can get to 160m after a few changes. 

I am on heavy clay that is now going from concrete hardness to mush. A good time to try a loop on the ground that can be just below the surface so my neighbours don't trip on it and the tractor mower doesn't eat it! Been wanting to try one. If I positioned it near to the base of the driven flagpole I could try it out as a counterpoise. Wouldn't be hard to isolate the antenna from the "van" ground. Nor would it be hard to compare Tx performance using the counterpoise only or the "van" ground.

I agree, experimenting is fun and a learning experience. What I lack is time more than anything.

Regards,

Paul.