Description
This antenna design has demonstrated remarkable versatility for shortwave listeners and amateur radio operators alike. The antenna comprises a 20 meter wire radiator and a 49:1 unun to match the load on the harmonically related 40, 20, 15 and 10 metre amateur bands. The antenna will resonate on these bands once a height of at least 1 meter is achieved. This design ensures the maximum SWR on these bands d0es not exceed 1.5:1. Use of an antenna tuner would improve this. Shortening the radiator to 10 metres in length (by folding the wire back on itself) will allow operation on 20, 15 and 10 metre bands. As resonance can be achieved at heights over 1 metre above the ground, a variety of mounting systems are possible. A single mounting point is the only requirement. The antenna is rated at 100W PEP (for 30 minutes maximum). Due to heat loss in the ferrite core used, higher power is not recommended. The antenna is supplied with a fibreglass insulator, supporting cord, stainless lug for counterpoise connection. We also include 2 x BNC female to PL-259 adators and a BNC female to 3.5mm phono adaptor.We recommend the use of a choke to block RF on the shield of the coaxial cable returning to the receiver/transceiver. To reduce the possibility of RF feedback and reduce common mode noise, use our Q3500P common mode choke. This should be placed approximately 6 metres away from the unun (frequency/band dependant).
