KL7JR'S Confined Space Stealthy Loop 6-20M
I can't say "I love loops"
The simplicity of installation and cost to build are hard to beat. Benefits aremulti-band capability,omni-directional coverage (if that's your fancy) and gainfrom some loops.
This is antenna project is another take off of my tried and proven vertical loop design used indoors and outdoors, but this time to fit a small space and be as "unseen" as possible from our island oasis condominium in the Dominican Republic.
Our patio space, shown in the photo above, now is about 16 ft long x 8 feet wide with a ceiling height of 15 feet in our newly purchased condo, occupies the top floor (3rd) of an ocean facing building.
Not many options for antennas, and using Hamstick type antennas was my last resort. I wanted a full wave vertical loop for 20m but the coils then had to be very long which exceeded the 30% rule (ie-do not make the coils longer than 30% of the wire antenna length).
Yes, I tried stretching it to 50% and it did not work out as I was merely talking to myself most of the time!
An easy fix for me was cutting out some wire (oh, I used white colored wire for the entire antenna to match the patio paint!) on the coils to arrive at 3/4 wavelength and re-stretching the antenna.
I now have a square, or almost square loop measuring 13' horizontal x 12' vertical and a 2 foot long coil #14 wire (wound on 1" scrap PVC pipe) in each of the vertical radiators.
Using the formula, 1005 divided by frequency we arrive at 53 feet for a 3/4 wavelength antenna set for 14.250 MHz (1005 div. by 14.250=70.5 feet times .75=53 feet). 13' x2 plus 12'x2=50', and allow 3 feet for the 2 coils (I used 2 feet/coil). I used an air choke (6-8 wraps coax on 6 inch dia.) at the feed point to eliminate stray RFI especially out of the neighbor's TV set!
It is shown in the photo below.
After a year of operating with the loop, someone from below finally noticed"something" and asked what the ropes were for. My flower trellis I quickly replied!
A trip to the plant shop for some fake flower vines were in order as shown in the photo above. I'm in good shapeagain until someone asks where to get flowering plants year-around, hi hi!
working DX all over the world again (10-20m, and hopefully 6m soon!) from
this QTH now 1 floor higher than before. The top of the loop is right at
40 feet above ground and the ocean fishing hole is only 120 feet away
Come on experiment. You'll be surprised with what a little wire will do (don't be afraid to reduce the loop if you have to)!
73, Yukon John HI3/KL7JR
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