HF Loop Antennas and Mounting Height

[Phil_KD0SCJ]

I have been using an MLA-30+ loop for a few months now and getting very pleasing performance with an RSPdx. I'm getting ready to take the next step which is a T2FD (which would be up now except for a late snow where I live this week). If the T2FD beats the MLA-30+, then I'm headed further in that direction, probably going from a 45' T2DF to whatever the next step is... 90 or 100 feet.

On the other hand, if the MLA-30+ is still better (a distinct possibility because of unavoidable RFI in my general area) then I'm going to an MFJ-1886 loop. I have seen schematics of the top 5 or so loops and I like the MFJ-1886 amplifier the most.

Now, I'm in the planning stages on the path that I might end up with the MFJ-1886. I have watched a lot of videos on loop antennas, read a lot of forum threads, but there's not much of a consensus that I can see regarding mounting height. MFJ tech support gave me a curious answer, they said they like to see 35 feet on all their antennas. I have seen people doing all kinds of A/B testing for different loops but nothing on height. I saw a guy, he had it at 6 feet and at 20 feet in two different videos but didn't even comment about the height change. I have done a little testing for height on the MLA-30+ and it does not like heights at all, decreases SNR from 5' to 15' height very noticeably. Has anybody done, or can point at any data-driven factual work on this subject?

Thank you!

~Phil

 

[bearcatrp]

Will be watching this thread as my next antenna is a loop. Have watched many you tube videos and have seen them at different heights. Best guess is to try different heights and see what you find out.

 

[Marcy57]

I have been using an MLA-30+ loop for a few months now and getting very pleasing performance with an RSPdx. I'm getting ready to take the next step which is a T2FD (which would be up now except for a late snow where I live this week). If the T2FD beats the MLA-30+, then I'm headed further in that direction, probably going from a 45' T2DF to whatever the next step is... 90 or 100 feet.

On the other hand, if the MLA-30+ is still better (a distinct possibility because of unavoidable RFI in my general area) then I'm going to an MFJ-1886 loop. I have seen schematics of the top 5 or so loops and I like the MFJ-1886 amplifier the most.

Now, I'm in the planning stages on the path that I might end up with the MFJ-1886. I have watched a lot of videos on loop antennas, read a lot of forum threads, but there's not much of a consensus that I can see regarding mounting height. MFJ tech support gave me a curious answer, they said they like to see 35 feet on all their antennas. I have seen people doing all kinds of A/B testing for different loops but nothing on height. I saw a guy, he had it at 6 feet and at 20 feet in two different videos but didn't even comment about the height change. I have done a little testing for height on the MLA-30+ and it does not like heights at all, decreases SNR from 5' to 15' height very noticeably. Has anybody done, or can point at any data-driven factual work on this subject?

Thank you!
I can tell you mine is on the ground almost and works great ...I do not think height is better for a loop but everybodys qth is different ...in my case getting it "farther out" away from the house was better and low to the ground...good luck...73,s Marcy
~

 

[bearcatrp]

Marcy, how long is your coax to your loop?

 

[Marcy57]

I ordered 100 ft. from cablexperts and so the run is
abt 80ft. approx. ..maybe this pic shows it a little?
better ...not trying to be redundant just trying to
give you some idea that it is a long run to get it
away from the house which I think is best...73,s Marcy

 

[bearcatrp]

Thanks

 

[Turbo68]

Hi Phil I use to have my loops around 5 metres performance wasn’t as good as what it is now lower to the ground main interest for me is hf aircraft MFJ 1886,Wellbrook ALA1530LN,W6LVP.

 

[ka3jjz]

You are correct, Marcy, alltho that is true of any HF antenna, not just loops.

Joe Carr has an excellent book on loops, and if you want to learn about how they work, it's a very good place to start.

Joe Carr's Loop Antenna Handbook By Joseph Carr K4IPV

Mike

 

[Marcy57]

Hi Phil I use to have my loops around 5 metres performance wasn’t as good as what it is now lower to the ground main interest for me is hf aircraft MFJ 1886,Wellbrook ALA1530LN,W6LVP.

I,m jealous nicer set up than mine...lol! ...marcy

 

[Phil_KD0SCJ]

Hi Phil I use to have my loops around 5 metres performance wasn’t as good as what it is now lower to the ground main interest for me is hf aircraft MFJ 1886,Wellbrook ALA1530LN,W6LVP.

Would you mind doing a short compare/contrast on the MFJ vs the Wellbrook? Also the MFJ has been through 3 revisions, how old is yours? I would be most grateful to hear your thoughts because I narrowed my choice down to these two and the MFJ won based on amplifier design but I'm not an EE or anything, and the Wellbrook is a more challenging purchase because it's an import from the UK. But, if you can tell me the Wellbrook is noticably better in performance and/or construction, I'd be very happy to know that. Thank you!

 

[Phil_KD0SCJ]

You are correct, Marcy, alltho that is true of any HF antenna, not just loops.

Joe Carr has an excellent book on loops, and if you want to learn about how they work, it's a very good place to start.

Joe Carr's Loop Antenna Handbook By Joseph Carr K4IPV

Mike

Great advice, I just ordered a copy... thank you!

 

[Phil_KD0SCJ]

I ordered 100 ft. from cablexperts and so the run is
abt 80ft. approx. ..maybe this pic shows it a little?
better ...not trying to be redundant just trying to
give you some idea that it is a long run to get it
away from the house which I think is best...73,s Marcy

Marcy, I see you have yours on a rotator, how is that working for you? I'm asking because the common word is that loops are highly directional, but my MLA-30+ doesn't seem that way. It's hard to tell, you know, I try and average some SNR over 5 minutes, give it a turn and measure again, would be much easier with a rotator obviously. Thank you for your thoughts too Marcy!

 

[Phil_KD0SCJ]

So... everyone posting so far is getting good/great results running a low antenna height, very interesting. This is not a trivial thing for me, and I'll explain why. Right now, I have two 20 foot masts available, and they are 100' apart with one mast within just a few feet of building where my receiver will ultimately be located... and obviously the other mast way out in nowhere on the edge of my property line. These are leftovers from a SWL attempt 15 years ago using a ultra-simple longwire and a Kenwood R-1000 receiver. Anyway, the mast that is close to the receiver was going to end up hosting either a loop or a VHF/UHF discone. So, this is good, I would much rather have a lightweight discone up there and keep loop a little more sheltered. Thank you all!

 

[Marcy57]

It is a cheap Channel Master rotator...not sure if they still are available...?
works great at nulling completely nulls out my landlords track lighting
it freezes up sometimes in the winter if like under 30F but maybe with
a better more expensive rotator that would not happen not sure? I use
my T2FD (33ft. long) above like 10 mhz but below that the wire brings
in too much local crap so thats where I use the loop , I cannot see having
a loop without a rotator unless you have zero qrm? this is a pic of my
Wellbrook loop (not a great pic sri!) in 2006 on my porch it was 2nd
hand and ran into some issues so I got Pixel loop (I thought the Wellbrook was a
little quieter at my qth!) ....ok good luck ..73,s Marcy

 

[Phil_KD0SCJ]

It is a cheap Channel Master rotator...not sure if they still are available...?
works great at nulling completely nulls out my landlords track lighting
it freezes up sometimes in the winter if like under 30F but maybe with
a better more expensive rotator that would not happen not sure? I use
my T2FD (33ft. long) above like 10 mhz but below that the wire brings
in too much local crap so thats where I use the loop , I cannot see having
a loop without a rotator unless you have zero qrm? this is a pic of my
Wellbrook loop (not a great pic sri!) in 2006 on my porch it was 2nd
hand and ran into some issues so I got Pixel loop (I thought the Wellbrook was a
little quieter at my qth!) ....ok good luck ..73,s Marcy

I may end up doing some ultra-cheap rotator this summer just to test. A permanent rotator in my situation would be a challenge, and I love challenges, but this is a whopper. Where I live, it is below 30F a lot... it's below 0F a lot, it's not unusual to have entire weeks of -25F. I may end up building something for the occasion. I'd rather try and build something than buy into some industrial strength rotator for a 1 pound antenna. Thanks for the reply, 73's

 

[Marcy57]

I would ask some other people on here or on the ham section abt the
rotator freezing up ....maybe it,s just mine plus I,m in the "Pine
Barren" area so in the woods it,s always colder...check out what
some other ops say....73,s Marcy

 

[iMONITOR]

Hi Phil I use to have my loops around 5 metres performance wasn’t as good as what it is now lower to the ground main interest for me is hf aircraft MFJ 1886,Wellbrook ALA1530LN,W6LVP.

I'm surprised they work mounted so close together like that.

 

[Marcy57]

I'm surprised they work mounted so close together like that.

I was wondering the same thing??

 

[bearcatrp]

Would love to see a comparison on those 3 loops. Am still considering the MFJ. Was scratching my head seeing 3 loops close together.

 

[bearcatrp]

Last time I checked, the MFJ was out of stock as they were filling back orders. Just emailed them to see if they have any in stock. Looks like a solid loop from what I have read.