Twin Loop Antenna

Give this home-made twin loop for 2m a tiy — and be surprised!

The full-wave loop antenna, with its large capture area, good signal/noise ratio, and excellent low-angle transmitting characteristics, is about as good as an antenna can get

That's what I thought until 1 realized that doubling the capture area with two fall-wave loops ted simultaneous!\ is even better Sev-

eral years ago. I replaced my 2-meter J-pole with a 2-element quad, and I was very pleased with the performance of this antenna upgrade. Now that I have replaced the 2-element quad with the twin loop antenna, I am even more pleased. Scratch} signals from outlying areas are now register-ins! 3/4 scale on the S-meter Now I

can hear everybody on the local 2-meter simplex net and get a gtnxl signal back to them with 5 watts, I chose to make this antenna from I/2-inch copper tubing because of its good conductivity and large surface area,

Here is a 2m antenna 1 constructed from info that I got from VV7YP of western Wyoming. Of course, I changed it all around to suit my purposes, but the idea is the same.

W7YP had a 17m double delta. It was described to me as a \V with a horizontal line across the top, but the center apex of the W did not connect to the horizontal line. It is ted with 50-ohm coax. The outer braid connects to the center apex of the W, and the center conductor feeds to the center of the horizontal tine, directly above the apex; In this way, two lull-wave loops are fed simultaneously, one to the left and one to the right, radial inn a ureat signal, and beinn outstanding on recehe. The impedance is near 50 ohms.

Twin Loop Antenna

Photo A, 2m twin loop antenna.

30 73 Amateur Radio Today * August 2002

Photo A, 2m twin loop antenna.

30 73 Amateur Radio Today * August 2002

Twin Delta Loop Antenna
Photo H, Copper snaps.

The double delta idea can he constructed in \arious ways. I decided to design and huikl a 2m version, w hich I will share with you, hat you can use your own imagination on band, materials, and design.

My 2m twin loop antenna has two square limps made from I/2-inch cop per plumbing tubing (type M) and eight elbows. After sweat-soldering the eight elbows and eight straight pieces (20-f/4 inches long) together on a flat surface, it will resemble a figure 8 (Photo A). Use the armstrong method to spread it apart in the middle so that there is a 1-inch yap. Cut a piece of I/4-inch plastic to 9-1/4 inches by 10-1/2 inches and put a 5/8-inch hole in the center for the SO-239 connector. The antenna is secured to the plastic using four copper straps, and It)-32 screws and nuts. Position the copper straps so that there is room to mount the I-1/4-inch dovsel mast to the plastic (Photo B), The dowel is 3 feet long, and has a flat area where it mounts to the plastic using two 10-32 screws and nuts as shown in Photo C,

Tuning

The SO-23^ is connected to the antenna feedpoints with #14 stranded antenna wire. One wire is kept as short as possible, but in connecting the center conductor use a piece of wire 4-1/2 inches long. Shape this wire like a U (Photo D), It can be lengthened or shortened to fine-tune the antenna to ¡46 MHz. This tuning loop also lowers the SWR, although I don't know why. My twin loop antenna has under 1,2-U>- i SWR across the 2m band. It is bidirectional favoring the directions broadside to ihe loops, hut reception and transmission to the sides is still nood.

The Gordon West Study Guides

Examination Test Questions & Answers for General Class and hxtra Class w ith explanations of the answ ers

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Omega Sales

P.O. Box 376 Jaffrey, NH 03452 800-467-7237

Sav You Saw it In 73!

Photo C\ The dowel is mounted to the plastic by two 10 32 screws and nuts.

Photo IX A 4-1/2-inch-long piece of number 14 stranded antenna wire is shaped like a "f/M to form a tuning loop for the antenna>

Photo C\ The dowel is mounted to the plastic by two 10 32 screws and nuts.

Photo IX A 4-1/2-inch-long piece of number 14 stranded antenna wire is shaped like a "f/M to form a tuning loop for the antenna>

Cart Markle K8JHQ 11570 Taylor Wells Rd. Clairdon OH 44024-8910

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