Wide Area Coverage

"We need better coverage" is the most common request in radio, and the most commonly answered by buying the wrong thing. Coverage is designed, measured and verified.

Antenna height, first and by a wide margin. The radio horizon in kilometres is approximately 4.12 × √h, with h in metres. Twenty extra metres of mast beats a doubling of transmit power in almost every case.

Terrain and structures. Hills block, valleys shadow, reinforced concrete attenuates, and metal-clad industrial buildings can be nearly opaque at UHF.

Receiver sensitivity. The link works in both directions, and the weak direction is normally the handportable transmitting a few watts from body height back to the repeater. A system designed only on the downlink will have users who can hear and cannot be heard.

Feeder and connectors. A long run of thin coaxial cable, or one badly made connector, can discard more signal than the power amplifier produces.

Transmit power, last. It is the specification printed on the box and the least significant of the five.

1. Define the requirement. Which areas, to what reliability, for which user types — handportable indoors is a far harder target than a vehicle radio outdoors. 2. Terrain and clutter modelling. Elevation and land-use data produce a predicted coverage map before anything is ordered. 3. Site survey. Candidate antenna positions assessed for height, access, power, structural capacity and backhaul. 4. Link budget. Calculated for the weakest realistic case, not the best one. 5. Design. Number and position of repeaters, antenna types, feeder specification. 6. Frequency planning and BTK licensing. 7. Installation and commissioning. 8. Verification measurement, with a report comparing measured signal against the plan.

Step 8 is where a project becomes accountable. Without it, "the coverage is fine" is an opinion.

Obstruction, multipath cancellation, enclosure attenuation, or simply the edge of coverage. They have different causes and different fixes, and identifying which one you have takes a measurement — which is cheaper than the amplifier that would not have helped.

Coverage also changes over time. A new building, a grown treeline or a re-clad roof will alter a picture that was correct at handover. Periodic re-measurement is part of maintaining a system, not a sign that the original design was wrong.

Prediction map, site survey report, link budget, design, licence file, commissioning records and a measured verification report. Get in touch to have your site assessed.