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A Helical Loop Antenna for the 20-meters Band

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ANTENTOP- 01- 2004, # 005 A Helical Loop Antenna for the 20-meters Band




By Vladimir Kuz'min, UA9JKW,




Two years back I have moved to Nefteyugansk (Russia, Siberia) where I could not receive the sanction to installation for a full-sized HF- antenna on the roof of my house. , So I began to do experimenters with short indoors antennas. Most success design of my indoor antenna is a design similar to Fig. 59, given in Reference 1.



I have used an inch OD plastic pipe to the form of the antennal. The pipe was bent in a hoop near1 meter diameter. Antenna has 580 turns (near 61 meters of length) of multicore isolated wire of 3 mm diameter with thickness of isolation of 1 mm. So, the spacing between turns is 2 mm. Antenna has SWR 1:1 to 50-Ohm coaxial cable to 14.100, bandwidth to SWR 1:1.5 is 300-kHz. I use a simple symmetrical device- 3 turns on a TV yoke ferrite core. Space from the antenna to the ceil is near 25 centimeters.



The antenna has quite good directed properties at rotation within 30-90 degrees the force of signals varied to 1-1,5 points on mine S-meter. I use a YAESU FT840 for my work in the ether. Change of polarization (at rotation of the antenna on the vertical side) appreciable changes has not given as well as change of feeding points has not given large change in the force of signals.

Helical Loop Antenna




Figure 58 & 59 from Reference 1




Page 60


60 61 62




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