SMALL LOOP ANTENNA

This design is for a loop antenna suitable for TX and Rx on 80m and 160m. This is simply a copy of a design by Harry Lythall (SM0VPO) at the following link:
80 METER FRAME ANTENNA.

Below are some close up pictures of my version. I found I had to remove one of the turns to get it to resonate on the top end of 80m for SSB DX work. Its a great antenna and its sharp null provides a wonderfull drop in noise to bring the DX in! - Thank you Harry!

Note: Athough the antenna has been varnished a similar antenna did not fare well outside so use this indoors for RX, see end of page for an outside version.

Some thoughts about the 80m band

small HF loop

The complete small 80m loop antenna. It sits on a weighted tripod and can easily be rotated for null.



portable antennas

Showing a corner of the loop and also part of the coupling coil positioned using nylon cord. The wires are feed through holes drilled in the four spreader arms. The wood structure was varnished after assembly which also helped to secure the windings.



portable antennas

Showing the high voltage capacitor with reduction drive and waterproof enclosure. The loop connections go in at the bottom of the box through long sleeve rubber gromets.



portable antennas

Connection of the 50 ohm coax to the triangular coupling coil.



portable antennas

The central support showing the butterfly nut fixing to the tripod mast.





Links:
home-made tripod details

mini HF loop

back to G1EXG's Radio page


outside loop

Another version of the LF loop made from plastic water pipes and connections. You can just make out the motorised capacitor through the window of the waterproof box. I made a wooden version of the outside loop but although it was varnished a couple of times its performance degraded over the months which I put down to water absorption in the wooden framework (the Q reduced and it became 'deaf'). I am hoping this plastic version will last longer. I use this only for Rx as the current capacitor is quite closed spaced. I have since made the wires to the capacitor much more tidy - which I hope will improve the null.


new 12 SWG wire and faraday screen

In March 2010 I change the household type wiring for solid 12 SWG enamalled copper wire, changed the capacitor for a more
wide-spaced device and also changed the coupling coil for a coaxial faraday screen type (at center, ca. 140 cm circumference - gave very good SWR on 80m band).

Some thoughts about the 80m band



THE CREATIVE SCIENCE CENTRE

Dr Jonathan Hare, Brighton, East Sussex. BN1 9QJ.

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