I hear of operators quite often that need an antenna for HF, but live in a restricted
subdivision. This means they cannot have obvious antennas, obviously! I hear a lot of
advice, most are geared toward a dipole in the attic or a flag pole vertical.
All systems have there unique pros and cons. But I recall seeing an operator that
encircled his roof with wire and made a loop from it. I searched and searched, but
could not find the article agian. Well, being the tinkerer that I am and having the
supplies I needed, I decided to build the "hidden house loop", test it on the air
and post it if the results were promising.
As you may guess, since you are reading this the results must have been good. Good enough to
go through the trouble of building and posting the article. The formula for a loop antenna is
1005/Freq in Mhz = length in feet. For 40m, that is 143.5 feet of wire.
We live in a fairly small house with a typical roof, the house is 40ft wide and 24ft long,
giving a 136ft parameter. Include the slope of the roof to follow and I guess it would be
about the 143 feet or so needed for a 40m loop.
My attack plan for the project is pretty much, "build it like a doublet and work it!" That is,
have the antenna at least resonant on the target band, feed it with balanced line and work
it multiband. That was the desired outcome anyway. So I did just that. I encircled the
roof with #14 insulated stranded and brought it back to 25ft of 300ohm twinlead from Radio Shack.
I took that to my home brew 4:1 air core BALUN, coax back to the shack (abt 20ft), ran it
though an LDG Z-100 and started tuning on 40m.
Holy cow, I do not think Ive ever built an antenna that tuned this low... Abt 1.2:1! All of
40m tunes up. So I check the other bands and 40m-10m tunes up very nicely. So I try 80m...
Keeping in mind the antenna is 1/2 the length needed for an 80m loop I didnt expect much,
however it did tune all of 80m very nicely. That does not mean much, I learned the hard way...
I can tune a dummy load to low SWR, but that doesnt mean it will radiate!
Condx has been horrible the last several days, and over the course of the following days
I would test this on several bands to get a feel for how well it performed before posting
this article. Results are that on 40m, it typically worked very well usually swapping
equal RSTs with other stations (599 for a 599, 579 for a 579, etc.). That usually indicates
it is working reasonably well. It was only last night I finally cabbaged up a contact
on 80m. I didnt expect much, but I got good reports... however I was about 2 s units down
from the other station. Well, that is okay... 80m is at least workable. One contact on
40m SSB gave the the time to go out and switch over to my 90ft Doublet and I was abt 2 s
units UP from the hidden house loop.
Several things we need to keep in mind... The idea of this antenna is number 1, stealth.
If you can, put up a long wire antenna as high as you can for best results. However, not
everyone can do this. 2, be able to work multiband. Both aspects were accomplished. However,
RF inside the house was present. No promises how it will interfere with other devices
so you will need to keep that in mind. Also keep in mind, this install is only abt 15ft
above ground... Getting it to work as well as it did was not expected.
Start off with leaving a tail at the start point.
Start tucking wire under the shingles, tuck and run.
I know.. the gutters are a mess, but.. look here.
All that is invloved is tucking the wire under the shingles.
My dedicated assistant.
No staples or special clamps are used, just tuck
the wire. It should hold no problems.
1/2 way across the back of the house. This is
not that hard of a project, it just takes time.
Keep going all the way around, nothing special,
just tucking wire under shingles.
Just another view
About 45 minutes later, I am back where I started.
Feedline in place, a short screw anchors the top.
Ready for solder and trimming.
I didnt like the way the wires were able to sway,
so I anchored one of the pigtails.
All done!
Back to my HB 4:1 BALUN (as seen else where on
this website).
The bottom is anchored with a short screw also.
The twinlead lays flat along the house is is hardly
noticable at all.
From the back angle, you can hardly see
the black wire.
Foul weather about to roll in... but anyway,
can you spot the HF antenna?
Further operations indicate that Id rather switch back over to my doublet, it does a good measure better, however I am pretty happy with the "W4INF Hidden House Loop"! It listens and talks very good for what it is, it was very inexpensive and pretty easy to put up. As an extra bonus, I do not 'need' to disconnect the rig when storms roll in... I figure if the hidden loop takes a hit, I have more worries than the rig getting toasted. I doubt it would attract lightning any more than the gutters would, but much less than a 50ft plus roll up tower. Also, even under strong winds (we recetly had 45mph gust) the antenna is not likely to come down or break.