MULTIBAND LOOP ANTENNA 80m - 10m

Homebrew Loop antenna for ham radio frequencies above 3.5 MHz (or 1.8MHz when modification is used). Construction details for low visibility (stealth) installation including coax feed line; photos shows what happens to the long spans of light wire subjected to heavy icing loads. Antenna functioned during and after the ice storm and returned to original position.

This antenna was made in October of 2009 by extending an existing 135 ft long 80 meter dipole. I used the loop briefly last fall in the 285 ft closed loop configuration with excellent results. For most of the winter, I have kept the 25 ft isolation section open so the antenna functions as a half-wave dipole on 160m. In this 260 foot configuration, the ATU will still tune the antenna on 3.5MHz and higher frequencies also (for example it works as a 2-wavelength loop on 7 mHz) but most of the comparison tests I have made on 80 and 40meters show that the 285 ft closed loop is much better than the 260 ft doublet above 3.5MHz.

I have had the antenna back in the close loop configuration since February 20th, 2010. It was stuck to the roof for about ten days after the ice storm ;-)

73 de NG9D.

Category:

Science & Technology

Tags:

• multiband
• homebrew
• ham
• radio
• antenna
• loop
• amateur
• stealth
• cw
• Morse
• code
• practice

[KC9SYJ]

I am thinking about putting up an antenna similar to yours and wondering if the internal tuner on my Yaesu FT-950 would be able to tune this antenna without the need for an external tuner. I am wanting to work mostly the 40,20,17,15,and 10 meter bands with one antenna rather than string up about five different dipoles to cover those same bands!

[NG9D]

ARRL Antenna Handbook 20th ed says use 450 ohm open wire feeder based on analysis. But 1991 and 1993 ARRL Handbook for Radio Amateurs show coax feed. I think a full-wave loop located horizontally about 0.1 to 0.2 wavelengths above ground presents a relatively low feedpoint impedance matched well with coax. I used an external tuner, and the cable was easy to route. QRP power levels netted many good signal reports. I figure if it tunes 1.0:1 and gets good signal reports with 3 Watts, it works.

[oldude45]

How do you add or remove the 160 isolation? Or is it permanent?

[NG9D]

Thanks for the question. The antenna has two sets of jumpers. Each of the jumpers has alligator clips to short the insulator and make it a closed loop ~285 feet around. When the jumpers are not connected, the 25 foot section opposite the feed point is isolated making a halo shaped doublet about 260 feet long. Of course this requires access to the antenna which can be provided by simply lowering it to the ground. I keep it in the closed loop configuration for best 80 - 10m results. 73 de NG9D

[NG9D]

@oldude45 Thanks for the question. The 25 foot section is isolated by a pair of insulators. Jumper wires at each insulator with alligator clips convert antenna from 260 ft doublet into 285 ft loop. The antenna is not high, but for safety I recommend lowering the antenna to change configuration. I normally keep it in the loop configuration for best 80 through 10 meter results. It is dramatically better as a loop. In the winter, I convert to the doublet configuration for 160m. 73 de NG9D . .

[parosite]

Amazing

[kn9ioutom]

NICE VIDEO ! 73 DE K9IOU CHICAGO

[demysaid]

when you say 'light wire', is that a specific gauge for stealth use?

[oldude45]

@NG9D thank you for the response. Just what I needed to know. I have the loop already and looking for a simple method to increase it's use.  You method is workable. Now to add a remote switch to manage the issue.

[NG9D]

@MEverett98Thanks for the question. The 25 foot section is isolated by a pair of insulators. Jumper wires at each insulator with alligator clips convert antenna from 260 ft doublet into 285 ft loop. The antenna is not high, but for safety I recommend lowering the antenna to change configuration. I normally keep it in the loop configuration for best 80 through 10 meter results. It is dramatically better as a loop. In the winter, I convert to the doublet configuration for 160m. 73 de NG9D . .