TETRA Antenna Buying Guide for UK Emergency Services

Selecting the wrong antenna for a police car, fire engine, or ambulance can undermine years of investment in mission-critical communications infrastructure. In the UK, emergency services are managing one of the most significant communications transitions in decades: the gradual shift towards the Emergency Services Network (ESN) whilst maintaining compatibility with existing TETRA systems. Getting antenna selection right is non-negotiable.

This guide provides practical, technical guidance for fleet managers, vehicle integrators, and field technicians responsible for equipping emergency service vehicles with reliable on-board antenna systems.

Understanding TETRA in UK Emergency Services

TETRA (Terrestrial Trunked Radio) has been the backbone of UK emergency service communications since the late 1990s. These systems operate in the 380–400 MHz band and offer encrypted, reliable communication with coverage across the vast majority of populated areas in the UK.

The Emergency Services Network (ESN) programme represents the next generation, adding 4G broadband capability alongside narrowband TETRA radio. Many vehicles will operate dual-mode systems (TETRA + ESN) for several years, placing specific demands on antenna design and installation.

Omnidirectional Antennas: When They Work Well

Omnidirectional TETRA antennas radiate equally in all horizontal directions — the practical choice for most emergency service mobile units in urban areas with good base station coverage. Browse Renair's range of omnidirectional antennas for vehicle applications.

Key advantages

• Simpler installation — no orientation adjustment required
• Lower cost than directional alternatives
• Works equally well in any direction of travel
• Suits applications where vehicle heading is unpredictable (fire, police rapid response, ambulance)

Typical specifications

• Gain: 2–4 dBi
• Impedance: 50 ohms nominal
• VSWR: <2.0:1 across TETRA band
• Radiation pattern: near-doughnut shape in azimuth

Directional Antennas: Gain and Range Trade-offs

Directional TETRA antennas concentrate radio energy in a specific direction, offering higher gain (typically 5–8 dBi) but requiring the vehicle to face the base station for maximum performance. See Renair's directional antenna range.

When directional makes sense: Fixed installations (control rooms, training centres) or vehicles with predictable routes such as transport recovery vehicles on motorways. For typical urban emergency response, the inflexibility of a directional antenna generally outweighs range benefits.

ESN Dual-Band Considerations

ESN systems require both narrowband TETRA (380–400 MHz) and broadband LTE (700 MHz and 2600 MHz). Two options exist:

Option 1 — Dual-band antenna: A single antenna covering both TETRA and LTE bands. Simpler installation, but performance is typically compromised in at least one band.

Option 2 — Separate antennas: Dedicated TETRA antenna plus separate LTE antenna or MIMO array. Superior reliability, independent troubleshooting. Recommended for most emergency service fleet rollouts. Browse combination antennas or MIMO antenna options.

ESN compliance note: All antennas must be tested and certified to meet ESN compatibility standards. Verify type approval documentation when procuring antennas for ESN vehicles.

Mounting and Installation

Roof mounting is preferred for emergency vehicles — it provides best all-round coverage and least multipath interference. Roof drilling requires advance planning and proper weatherproofing. Renair supplies a range of mobile vehicle antenna mounts suitable for roof, bracket, and magnetic applications.

Ground plane note: TETRA antenna performance is highly sensitive to the ground plane. A roof-mounted antenna on a steel vehicle roof provides an excellent ground plane. Mounting on fibreglass or composite surfaces degrades performance — use an auxiliary ground plane (0.5–1 m² copper or aluminium mesh) if mounting on non-metallic surfaces.

Cable Selection and Loss

Cable loss directly impacts received signal strength — every 3 dB of loss roughly halves received signal power. Specify low-loss coaxial cable from the outset: RG-213 equivalent for runs up to 5 m, lower-loss options for longer runs. All external connectors must be rated to minimum IP65 and fully weatherproofed.

Common Installation Mistakes

• Inadequate grounding — always use solid mechanical fasteners and conductive contact, not sealant alone
• Coiled or kinked cable runs — route cable carefully, secured to prevent movement
• Wrong connector type — mismatched connectors introduce impedance discontinuities and loss
• Insufficient weatherproofing — water ingress will degrade the system over months
• Assuming one antenna suits all applications — select based on operational requirements, not specifications alone

Specification Checklist

• ☐ Application type: omnidirectional or directional? Fixed or mobile?
• ☐ TETRA band (380–400 MHz) compatibility confirmed?
• ☐ ESN dual-band (TETRA + LTE) capability required?
• ☐ Mounting location: roof, bracket, or temporary?
• ☐ Cable length and loss calculated?
• ☐ Connector type matched to radio equipment?
• ☐ Environmental rating confirmed (IP rating and temperature range)?
• ☐ Type approval documentation provided?

Next Steps

For ESN-certified TETRA and dual-band antennas engineered for UK emergency service vehicles, contact Renair's technical team for product selection guidance and installation support. Alternatively, browse the full Renair antenna product range or view our bespoke antenna design and manufacturing services.