Small transmitting loop for 1,8 – 6 MHz

Because of increasing noise levels in my neighborhood with S-meter readings seldom under S9 on the lower HF bands I have build this small loop. The loop consists of three turns of PVC insulated 15mm copper tubing in 1 meter diameter and there is a 500pF variable capacitor to tune the circuit into resonance. Noise/signal levels increased considerably compared to my other antennas and it is now possible for me to read weak stations on the lower bands. It is also possible to transmit with the antenna, but no more than 5-10 watts do to capacitor sparking.

Capacitor is hidden under the upper plastic bucket. The thin blue wire loop is the coupling loop feeding the feed line.
The 500pF capacitor works down to 3,5MHz. For 160 meters, 2000Pf is needed.

First edition: 24.06.2009
Lastest edit: 08.01.2012

4 comments on “Small transmitting loop for 1,8 – 6 MHz”

  1. Nice loop – there aren’t many online examples of small, multi-turn transmitting loops.

    Could you provide a close-up image of the capacitor mounting (under the bucket)? Having multiple turns complicates the mechanical mounting of the capacitor, and I’m curious how you did it.

  2. There is not really much to show under the bucket as there only is a small air-capacitor loosely connected with wires. I have however plans to get a motor driven vacuum-capacitor. But I have not yet had any success in finding suitable capacitor. 73 de LA6TPA

  3. You might consider building your own butterfly capacitor. There are lots of articles on the web, and if constructed well, they can approach the performance of a vacuum variable. I’m investigating this route now for my next loop.

  4. As qrp.gaijin said: “…there aren’t many online examples of small, multi-turn transmitting loops.”

    I was hoping there’d be more online since he wrote that but I have yet to find more.
    At least not any as encouraging and simply enjoyable as yours.

    I’d like to replicate your multi-turn small transmitting loop antenna shown here, however I want to see if I can use the spools of 3/8″ copper tubing I have laying dormant.

    I’ll appreciate sharing how you calculated the number of turns of tubular radiator for a specific diameter tubing. I just want to envision the scale of the radiator coil I’ll need to construct.

    Thanks again for an very down-to-earth and inspiring article!!
    73 de WB2HJK

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