something as high as you can find. << You also want the antenna to be at least 1/4 wavelength long for each band you plan to use. The second smallest number I measured was 2.7pF, derived from the self resonance at 2.72 MHz with the magnetizing inductance (measured at 25.8 H) with the secondary open and the output wire folded to a small 1/2 length. So for example 80m could range in length from 120 to 133 feet. 27.00 (27.00/Unit) Free Postage. All you need for a random wire antenna is some wire, your tuner, one or more supports up as high as you can get them to string the wire from the supports to the tuner, at least one or two insulatorsand a little time.