An Indoor HF Stealth Antenna

I found a way to have a reliable Indoor HF Antenna despite my antenna restrictions!

TS690SAT image

sgc230

SGC SG-230

I have always been what’s known as an “Appliance Operator” - With the SG-230 smart tuner I have an indoor “point and shoot” antenna for 160 - 10 meters. I have worked and confirmed enough contacts to apply for my first DXCC award.

In my quest to become active again on the HF bands, I constructed a wire loop antenna around my spare bedroom wall. The wire is fastened to the wall by some nylon “bow tie” wire hangers I found at a home center. They have a nail in the center and seem to hold 14awg stranded wire securely. With the wire drawn tight, they stand the wire off the wall by about 3/16”.

feed_pointI ran the wire up the wall in one corner from floor to ceiling and then I follow the ceiling around the room at 4” down from the top. When the end reached its starting point, I came back down the wall and spaced the two elements about 4” apart similar to ladder line. At the bottom, I attached my MFJ Versa Tuner.

With that in place, I ran a 50’ foot length of coax out to my kitchen table and set up my Kenwood TS-690S. Prior to transmitting, I would connect my MFJ Analyzer and pre-tune the tuner. It seemed to work but it was very narrow banded. In all, this antenna worked ok. First time on the air in six, years and I operated in the Canada Day CW contest. Operating “search and pounce” made for many trips to the other room for tuning up. In all I believe I mad 150 contacts that day. It made for a good “emergency preparedness” drill.

This went on for a few weeks until I broke down and bought an SGC Smart Tuner. After doing a lot of research, I found the SG-230 to be the best fit for my situation. It is a wire tuner that is fully automatic and can tune from 3.5 MHz to 30 MHz inclusive. Included in the manual were to designs that would work for my situation. Here are two possible configurations taken from the manual:

SGC_LoopThis configuration is similar to what I currently have except that it is indoors. I place the tuner in the corner of the room so its feed point is in the corner of the square on opposing walls with about 14 inches of separation. In the corners of the room, I use alligator clips to connect the runs of wire giving me the option to selectively add and remove wire changing it from a closed loop into a sort of folded dipole.

I find that it works reliably on the frequencies above 80 meters with only two walls connected as a dipole. For 80 meters, I connect the opposing walls giving me 2 “L” shaped legs of the dipole. I close the loop completely for 160 meters operation. The overall wire length in my situation is about 60 feet when running a closed loop based on a room size of 12’ x 12’.

Alternate_loopAn alternative to the loop design is suggested in the manual and was somewhat less than successful, but did net me some state side contacts. I found this layout, along with the closed loop, exhibited a higher noise level as it provided more of a vertical polarization. Noise levels were in excess of S-7 or so.

When running as a folded dipole the noise floor is more reasonable - in the range of S-3 to S-5. I plan to fabricate an X-brace to try this design again. I am sure that trying different feed points may make a difference. I am also trying an inverted L arrangement with a traveling counter poise around the floor to see what it does.

Living in an apartment as a ham has its disadvantages but you can get on the air. I have obtained my DXCC in less than 2 years. I have computerized my shack and am now looking into remote operation. I have successfully logged into my station while away for business and logged contacts. One of our club members operates strictly remote because of his antenna restrictions. My next change may be to buddy up with a family member or that best friend with all the open land and mooch a corner of the basement and a network connection for my remote.

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About the Author

k2zs_avatar

I’ve been licensed since 1982 when I passed my Novice exam and was given the call KA2QOZ.

My interests lean towards chasing DX and operating CW. I operate mobile HF with my Yaesu FT-100 when I can. Take a moment to browse through my site.

73 from Scott, K2ZS

Contact

If you're in Rochester, NY I can usually be found on:

 - 144.220Mhz USB
 - 145.11/144.51 WR2AHL Repeater

Otherwise, I can be found in the lower portions of the CW bands on HF.