Welcome to the Jarvis 2024 DXpedition | N5J

Antennas for Jarvis

We will be using five different antennas.

V8: A small, 25-foot tall vertical with two elevated counterpoises fed by an automatic tuner for 40 to 10 m.
      N6BT design.

V9 Dual Band 40/20 m Antenna: This antenna has two vertical wires that resonate at 7 and 14 MHz. Two sets of elevated radials make this antenna somewhat ground independent.

V10: A 38-foot vertical, fed via an automatic tuner that covers 80 to 10 m. The antenna uses salt-water for ground. Based on the DXengineering ATK65A kit.

V11: 45-foot vertical fed via an automatic tuner that covers 160 to 10 m. Based on the DXengineering ATK65A kit. This is a “bird-friendly” 160 m antenna that we hope will provide good enough performance despite it being only 1/12 of the wavelength (instead of ¼). 

The V8 and V9 antennas do not require a ground. Both the V10 and V11 have large aluminum bases that stand in or near salt-water and connected to the salt-water for a an almost perfect ground. No radials.

Main Antennas for Jarvis

The three main antennas. These have been skeletonized to minimize the danger to birds.

V8		V10		V11
20 feet tall Horizontal Counterpoises		42 feet tall Salt-water ground		45 feet tall Salt-water ground

 V8

N6BT design with a 100 W automatic tuner. The antenna is a vertical with two counterpoises at 3 feet above the ground. Performance is excellent from 30 to 10 meters when located near the water’s edge. The antenna is usable on 40 meters.

V10

12.7 m (42’) tall vertical that stands in salt –water close to the shore-line, on an aluminum base. Fed via a 500 W automatic tuner. Used on 80 to 10 m by the FT8 Local 2 and CW Remote 3 stations. Maximum gain is towards the water.

V11: 160 -10 m Vertical

This antenna was designed to give reasonable performance from 160 to 10 m despite being only 45 feet tall and “bird-friendly” – i.e. no top loading wires. The antenna is fed by a high performance 1 kW tuner (coupler). For 160 meters, instead of the usual top-loading wire(s), a large base loading inductor is used. This 34 uH inductor is wound on a 6” diameter form, which is 3 feet long. The inductor is automatically switched out by the antenna tuner on the 80 to 10 m bands. The wires forming a triable are fed via a second port of the antenna tuner on 20 to 10 meters, to provide low angle radiation on these higher bands The antenna stands on a large aluminum base that is in contact with the salt-water, which provides a good ground, making radials unnecessary.

V11 160 - 10 m Vertical