The Challenger is designed to be mounted directly on the ground or elevated on the roof. As is the case with the other GAP antennas since it does not require earth loss to obtain a 50 Ω match.!Roof mount does not gain any specific advantage due to the 'elevated ground' structure, but is possible if there's no garden etc. available.The CHALLENGER covers the bands 6/10/12/15/20 and 40m. Over 130KHz of bandwidth is provided on 80m!The antenna requires a counterpoise of three 7.5m wires. They may be buried or just scattered on the ground. Symmetrical deployment is not critical. Adding additional wire will not significantly improve performance.As described with the TITAN The operating center frequency on 80m is set by means of an integrated fixed capacity. Please specify the desired center frequency upon ordering. The standard setting is 3.65 MHz, other frequencies are available on request.