General information
The S.M4 is an array of four dipoles mounted on an aluminium mast.
Each folded dipole balun assembly and harness junction is completely encapsulated in poyurethane resin, preventing moisture ingress.
The dipoles can be easily oriented on site or before shipment to adjust between omnidirectional and directional patterns, and beam tilt is easily achieved via the parallel feed. The VHF antenna disassembles to reduce shipping costs, and the boom can be supplied in two parts if requested.
The balun assembly has been tested to BS5490:IP67.
Purchase via HQ recommended (compulsory for ICRC)
Specifications
|
Frequency range |
Typical: 155–175MHz or 176–192MHz |
|
Input impedance |
50 Ohm |
|
Typical bandwidth |
+/- 5.5% of Centre Frequency |
|
VSWR |
< 1.5:1 |
|
Front-to-back Ratio |
7 dB (offset) |
|
Maximum input power |
250 W |
|
Polarisation |
Vertical |
|
Forward gain |
Omni: 5.7 dBd
Offset: 8.7 dBd |
|
3dB Beamwidth |
E-Plane: 21°
H-Plane: 180° (offset) |
|
Standard connection |
3m length of RG213 with N female type connector |
|
Elements |
12.7mm dia. x 1.6mm wall aluminium alloy grade 6063T6 |
|
Support boom material |
VHF: 63.5mm dia. x 6.3mm wall aluminium alloy grade 6082T6 |
|
Fasteners |
Stainless steel grade A2-70 |
|
Dipole clamps |
Cast aluminium alloy |
|
Dipole adjustment |
M8 Stainless steel screws |
|
Saddle clamps |
Diecast Al/Zinc alloy |
|
Balun encapsulant |
Polyurethane resin U-600 |
|
Lightning protection |
Direct grounded |
|
Weight |
26kg |
|
Length |
6m |
|
Typical wind load @ 45m/s |
620N |
Spare parts and accessories
Latest update: 15/04/2020