Radar for boats – Installation, function, and best choice

Learn how radar works, the difference between Dome and Open Array, and how to install radar for maximum range and safety.

Radar stands for radio detection and ranging. It is an instrument that detects objects by transmitting RF energy and receiving reflections from these objects. Since radar uses microwaves with short wavelengths, the accuracy is very high. The reflected energy shows both the direction and distance to the object.

How does radar work?

Radar operates on a line of sight, meaning no obstacles should be in front of the antenna. Masts or antennas can create false targets and shadow zones on the radar screen. Installation is therefore crucial for performance.

Important installation principles

1. Mount the radar above the crew – radar beams are focused energy.
2. Avoid obstacles that can block the signal.
3. For multiple radars, at least 45 cm vertical separation is required.
4. The mounting location must support 6x the antenna's weight.
5. Recommended height: at least 8 feet above deck, max 30 feet above water.

Radar function and distance calculation

Microwaves travel in a straight line and are reflected back upon contact with an object. The distance is calculated using the formula:

D = (c * T) / 2

D = Distance, c = speed of light, T = time for the wave's round trip.

Dome Radar

Compact, lightweight, and energy-efficient – ideal for recreational boats. Has a wider beamwidth and lower cost.

Open Array Radar

Powerful with a narrow beam angle for better target definition. Common on commercial and military vessels. More expensive and heavier.

Radar bands – S-band and X-band

S-band: 2–4 GHz, longer wavelength, less attenuation, perfect for long-range and marine navigation.

X-band: 8–12 GHz, short wavelength, high precision, ideal for nearby targets.

The combination of both provides optimal coverage and accuracy.

Installation height and range

The radar's range is affected by the antenna's height. The higher the installation, the longer the line of sight. Calculation:

D = (√A1 + √A2) * 2.2

A1 = radar height, A2 = object height.

Summary

For best radar performance – choose the right type, mount correctly, and combine S-band and X-band for maximum safety and precision.