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There are several ways to feed a large (at least 1 wavelength in circumference) loop antenna.
Stan Gibilisco (W1GV) shows an easy way to use either 50 ohm or 75 ohm coaxial cable as your feedline. Although the loop can use 50 ohm feed line, the SWR would be approximately 2:1, assuming the loop's impedance measured between 100 and 120 ohms. The SWR would drop a bit if you used 75 ohm coaxial cable and a 50 ohm coaxial cable matching section.
With this arrangement, you would have an excellent monoband HF Loop. An antenna transmatch (i.e. "tuner") would allow use on a few other amateur radio bands.
For my 40 meter horizontal loop, I use 450 ohm ladder line into a balanced "tuner" to enable multiband capability from 40 meters through 10 meters. Either feed line arrangement should give you hours of excellent contacts, depending on the band and propagation at the time of use.
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Aloha es 73 de Russ (KH6JRM).