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Horizontally Polarised Omni-Directional Antenna


This omni-directional antenna is designed for monitoring of horizontally polarised RF signals in the frequency range 20 to 500 MHz. The band is covered by 2 antennas: a crossed-dipole fed in quadrature for the low frequencies, and a four-feed loop antenna for the upper band. The loop radiation pattern has a null at top and bottom, eliminating structure interactions that plague crossed-dipoles mounted with other antennas. A generous central cavity allows several large cables to be passed through the antenna, for feeding other bands or DF antennas higher up the stack. The substantial mast and flanges allow heavy antennas to be mounted above the omni. This antenna is part of the SYST-A0004 stack providing interferometric DF, vertical and horizontal polarisation monitoring in the range 20 to 3000 MHz.

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Frequency range Band A: 20 - 100 MHz Band B: 100 - 500 MHz
VSWR Band A: < 2:1 Band B: <15:1
Feed power handling 0.25 W
Nominal input impedance 50 O
Connector 2 x N-type female Supplied with N-M cables
Gain See graph
Gain variation over azimuth < 3 dB RMS
Polarisation Linear: horizontal
Dimensions (ϕ x h) 2.0 m x 1.0 m
Weight 22.5 kg
Mounting method 8 x M12 bolts in flanges
Wind survival 160 km/h as part of SYST-A0004
ative humidity (operational) < 95%
Salt / fog Yes
Vibration MIL-STD-810F vehicle

    Product Applications

    Signals Intelligence

    Design Features

  • Wideband horizontal omni. Smooth radiation patterns. Hollow centre core allows cables to pass through the antenna. Heavy aluminium tube to support further antennas above this omni.