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ST Series
Sloping Triangle Directional Antenna Series 3-30MHz & 5-30MHz

Rev : 01 | Rev date : 25 Nov 2021

These simple, low-cost, broadband horizontally polarized antennas are designed for medium to long-range point to point or sectorized transmission or receiving applications.


  • Characterized by an increase in gain and directivity when operated within the higher frequency band, the ST series provides an economical option to a full horizontal Log Periodic Dipole design.
  • The antenna is comprised of two sloping wires resistively terminated at the center point of the vee near ground level. The apex of the vee is supported by a suitable mast while the antenna is fed via a balun transformer at the masthead.
  • The ST330 model is available as an ST330S version which has a much reduced footprint for applications where the ground area may be an issue.
  • The ST series is available with or without mast systems of which two versions are available: Tubular Aluminium (MA): Triangular galvanized steel for high wind speed sites (MS).

For detailed model specifications and ordering information please contact RFS.


Technical features

Electrical Specifications

Frequency Range MHz3-303-305-30
Gain dBiRefer to graph
Elevation Radiation PatternRefer to plots
Azimuth Radiation PatternDirectional - Refer to plots
VSWR<2.5:1 max, <2:1 typical
Maximum Power Rating kW0.25 average, 1 PEP
1 average, 4 PEP
5 average, 20 PEP
Input ConnectorN-type socket (0.25kW)N-type socket (1kW)7/8" EIA (5kW)
Impedance Ω50

Mechanical Specifications

Mast Height m (ft)19 (62.3)15 (49.2)15.5 (50.8)
Antenna Ground Dimensionm (ft)100 (328.1) Vee length,
80 (262.5) Vee width *Note 1
50 (164.05) Vee length,
50 (164.05) Vee width *Note 1
80 (262.5) Vee length,
63 (206.7) Vee width *Note 1
Mast Guy Radius m (ft)14 (45.9)11 (36.1)11 (36.1)
Wind Survival Rating (No ice) km/h (mph)160kmh (100mph) with RFS Series MA mast *Note 2
230kmh (143mph) with RFS Series MS mast *Note 3


Material - MastMA Mast - Aluminium
MS Mast - Galvanised steel

External Document Links


Note 1. Additional space must be allowed for main mast guys
Note 2. Calculated in accordance with AS1170-1981, Part 2, "SAA Loading Code Wind Forces" and AS1664-1975, "SAA Aluminum Structures Code"
Note 3. Calculated in accordance with AS1170-1981, Part 2, "SAA Loading Code Wind Forces" and AS1250-1981 "SAA Steel Structure Code"