C&S Antennas: HF Dual Antenna Configuration

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The LFHP antenna is a HF wire antenna intended primarily for omni-directional skywave communications to a range of about 1000 miles, including short-range Near Vertical Incidence Skywave (NVIS) operation. The antenna is rated for 1kW continuous operation (a 0.4kW transformer is also available) and is broadband, with a VSWR not exceeding 2.2:1 over its specified frequency range. An antenna coupler is unnecessary. Viewed from above, the elements resemble a bow tie. In this configuration, the centre of the antenna beam over the lower portion of the HF band is directed straight upwards for optimum NVIS operation. Here, the radiation pattern is omnidirectional within ± 1dB over the frequency range 2 to 8 MHz at angles at or above 60° above the horizon. At higher frequencies, the antenna beam becomes approximately hemispherical, providing useful single-hop performance to about 1000 miles.

Four versions of the antenna are available, as below.
Model Number Frequency Range
LFHP1630 1.6 – 30 MHz
LFHP230 2 – 30 MHz
LFHP330 3 – 30 MHz
LFHP430 4 – 30 MHz

The antenna requires a suitable mast to be available as well as anchoring points at the appropriate positions at ground level to attach the antenna wires. Reference is made to a suitable mast available for use with the antennas.

The SVAP280/1E antenna is a permanent installation version of the CSA Sloping V tactical antenna and is designed to withstand extremes of wind and ice accretion. The antenna kit as supplied includes all the electrical parts but the end user must provide a support mast or tower and four smaller poles to support the antenna wires. The antenna kit consists of two wires 270 ft long that connect to an insulated spreader assembly that is itself suspended by two non-conducting strops from a mast. The wires are stretched out in a V configuration and terminate at ground level through a non-inductive load. The wires are supported at mid span and near the end by poles set in the ground; these give some support and restraint to the wires which would have to be excessively tensioned otherwise to keep them off the ground. Power is fed up the mast through a feeder cable (customer supply) to a transformer strapped to the spreader bar, the two antenna wires connect to the arms of the transformer. The antenna is designed to operate over the frequency range 2-30MHz with a direction of propagation away from the mast along a line bisecting the two wires.

General Specification
Frequency Range: 2MHz to 30MHz
Power Rating: 1kW
Transformer: 50 ohms, 50:600 ratio, N socket
Feeder Cable: URM67 (RG213U), N plug
Mast: 40 feet high connection required to accept a bow shackle with 1-1/8” pin.
Wires: 5mm galvanized steel wire strand impregnated with polypropylene to diameter 6.1mm, 1.8ton min breaking load per wire.
Resistors Two loads of 680 ohms, 180W wire wound, vitreous enamel, non-inductive, in parallel in each wire leg.
Resistors are individually cased and protected under an open framed cover.
Pole Top Insulators: Glass reinforced plastic structural I-beam section
Fittings: Galvanized steel shackles, thimbles, guy grips, hairpin anchors.