To make this loop take 20 feet of RG59 coax. Half way along the coax , At the point that will become the top of the loop, break the shield for 1 inch. Place a variable trimmer capacitor (400pf) inside a waterproof project box. I mounted mine on some wood, with a hole drilled for the trimmer shaft to sit in. I glued the trimmer cap to the wood.
Next, join the 2 centre conductors to the 2 trimmer tabs (see photos) Join the braids to each other & the braid on a short piece of RG59 to connect to a surface mount SO239 .
The centre of this short piece of coax should join the centre of the S0239 with the variable trimmer.
Finally, adjust the loop for resonance using an analyzer. Start with the trimmer screwed in, then gradually screw out, using an insulated screwdriver.
You can make formers for your loop & mount on a fence like myself, or on a rotator.