Loop Antenna + on 40m


Jon Hall
 

looking for advice / suggestions ...
I have the CCW loop antenna + with DC power unit. That is connected to sdrplay box.
I monitor from 160m - 2m and am well pleased with the results across this range.

I also have a efhw going down the garden.
Yes the wire is slightly better, but the loop works very well.
BUT [there's always a but]
On 40m the loop seems very deaf [all others bands are good]
The actual loop is the same length as the wire supplied, but I use a 1" stainlees steel strap.
Any ideas why only on 40m that I receive very little.

Regards, Jon.


Chris Moulding
 

Hi Jon,

It could be several things that affect the performance of your loop.

The first thing I would do would be to look at the background noise level and compare it with say 80m and 30m. 80m should be the highest figure, 40m next and 30m the lowest.

It that test checks as expected then maybe it's the time of day that you listen to 40m . I've always thought of the 40m band as being like Dr Jekylll and Mr Hyde! It can vary between a local NVIS band in daytime if the sunspots are high enough to an all out DX band at night If the daytime sunspot figure is not high enough then there is usually very little activity in daylight.

Another possibility is that it's being affected by your EFHW. I would hazard a guess that it's resonant on 40m. If so it's possible that it's blocking some RF on 40m from reaching your loop.

This can also work the other way. I once tested a version of a MiniWhip antenna which gave outstanding results on 40m. It was only later that I realised it was 2m from the end of a 40m dipole and it was capacitively coupled to the end of the dipole.

The immediate surroundings of an antenna can have some strange effects on it.

Regards,

Chris


Jon Hall
 

thanks for the comments Chris.
Good point about the efhw [yes 40m] that had'nt crossed my mind.
Its no real deal-breaker, I can just swop over as required.

Overall very impressed with the CCW Loop+ , a great companion for the sdrplay..
ATB, Jon