Technical Notes - Omni and Dipoles

LINKS: Flat Panel > Sector > Omni > Ultra Wideband > Helix > Primary Specification

Below: Vertical Polarisation, Circular Polarisation, Hemi Omni, Dipole, Blade

OMNI Antennas, VERTICAL polarisation

• VOA and OA series
• Gain up to 11dBi
• Frequencies up to 18GHz
• Centre fed to ensure peak gain remains on the horizon
omni group • Stable, ground plane independent radiation patterns
• Light weight but rugged, for harsh environments
• For special applications horizontally polarised high gain omnis can be developed

An omni antenna radiates full power 360° in the horizontal plane. Peak gain usually on the horizon.
All collinear omni antennas are centre-fed making them ground-plane independent and providing stable radiation patterns across the band.

High gain omnis can be produced by stacking and feeding more elements. This has the effect of reducing the elevation beamwidth.

By adjusting phase and amplitude to each element, sidelobes can be controlled and the elevation beam can be shaped to provide features such as null-fill or electrical tilt.

Collinear antennas combine light weight construction and environmental protection with rigid glass fibre radomes and aluminium mouting spigots.

Right: OA2-2.4V/1392, VOA7-36/1146, OA4-2.5V/1542

VOA4-1400/1130 VOA4-1800/1319 OA4-2.0V/1375 OA4-2.4V/1369
omni 1130 omni 1319 omni 1375 omni 1369


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OMNI Antennas CIRCULAR polarisation


Many applications benefit from circular polarisation to optimise performance, in particular ground to airborne applications. Circular polarised omni antennas are available with:

• Frequencies 400MHz to 14GHz
• Left or right circular polarisation
• Good axial ratios
• Bandwidths up to 15%

DSO3-24-54/1177 RCO3-1394/394 LCO5-3450-M01/1434
rco 1177 rco 0394 lco 1434


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HEMI OMNI Antennashoa 1486

Hemi omni antennas provide coverage over a hemisphere for applications that require a single antenna to cover a very wide area such as:
• Links to satellites and airborne platforms
• Air to ground links when inverted

These antennas feature:
• Circular or dual circular polarisation
• 2 to 3dBiC peak gain overhead
• 120° to 150° beamwidth
• Active or passive

Right: HOA2-159L/GPS/1486

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DIPOLE Antennas
Dipole antenna SVD2-3450/426
• EVD2 series - rugged dipoles with rigid glass fibre radome, most have N-type connectors
• SVD2 series - semi rigid with abrasion resistant rubberised coating, most have SMA connectors
• Vertical polarisation
• Gain 2dBi with elevation HPBW 80°
• Frequencies 300MHz to 12GHz

Traditional dipoles have omni-directional coverage, are rugged or flexible, with approximately 2dBi gain. Monopole and dipole antnnas have a 360° azimuth coverage and typically 80° elevation coverage.
They are balanced and independent of ground plane.

Right: EVD2-3.2/1401 and SVD2-2300/427

SVD2-3450/426 SVD2-7790/1243 SVD2-3350/1126 FVD2-2.8/1528 EVD2-1300/1395 EVD2-1600/530
Dipole antenna SVD2-3450/426 flexible dipole 1243 flexible dipole 1126 flexible dipole 1528 evd2 dipole 1395 evd2 dipole 0530

ruleDipole antenna SVD2-3450/426
BLADE Antennas

* Blade antennas can be as little as 2mm thick
• They may be housed in protective radomes
• Aerodynamic
• Light weight
• Specification as for dipole antenna
• Coverage can be omni-directional or directional, depending on the application requirements
.
Blade (printed circuit) antennas are suitable where a 2mm thick fully efficient antenna is needed.

Right: SBA-2.3V/1470 and SBA-900/1249

SBA-2295/1299 SBA-1480/1297 HDA-1275/1561 HDA-2.4V/1423 HDA-2450-FRA/1225 VOA5-2350/1403
blade SBA-2295/1299 blade 1297 blade 1561 blade 1423 blade 1225 blade 1403