HAM RADIO - Magnetic Loop Antenna 20m-40m
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- Опубліковано 4 лип 2024
- 15-240PF 2000V Single-unit Air Dielectric Variable Capacitor
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99.9% Copper Tube 1/2" OD x 7/16" ID 10 Ft, Tube Wall: 1/32"
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The vageries of magnetic loop antennas take a lot of learning . They are very effective in conditions where normal antennas struggle due to noise and poor propogation and the directionality of their gain means that you can pull signals out where none seem to be. I love mine ,especially for QRP , and have had some very surprising results . Keep at it - you will learn to love it as you get to know it better. (I now adjust mine instantly entirely by ear !). It's a bit like learning a musical instrument. 73 M7BLC
Nice project antenna. You may want to consider putting a 1:1 balun line insulation in the feed line coax at the antenna. MLAs are prone to common mode currents which will limit the amount of power you can apply to the antenna and limit the ability to get a good low swr. MLAs have very low radiation resistance so there can be 15 amps on the loop say at 30 watts plus thousands of volts on the capacitor. Soldering the loop to the capacitor will greatly improve efficiency and reduce mechanical resistance losses which is the biggest problem in loop design. I really like your project antenna. Great job and well engineered! Best 73s. Dan K1YPB - On the air since 1962
Nice MagLoop Almir, good Job on that. The capacitor should be on top and the small loop on the bottom. This reduces the receiver noise.Or Am I mistaken? Happy Weekend & 73 de Uncle Günter from across the Pond 💯🙋♂
Great information. I was thinking about a monoband loop antenna for 20m CW portion. Would it work with smaller capacitor or a RG213 as a capcitor? Is there a way to find how much capaticance is needed?
I have quite a lot of experience with magnetic loops. You can see the two loops I have in regular service on my QRZ page. MFJ made a loop tuning box that was rated for 100+ watts. I have used one to make portable field antennas on many occasions with excellent results.