First, an aiming station (possibly mounted on a vehicle) in the launching area directs a narrow radar or laser beam at the enemy aircraft or tank.
Early tracking radars generally use a beam a few degrees wide, which makes it easy to find the target as it moves about.
For example, earlier versions of the RIM-2 Terrier missile introduced in the 1950s were beam riders, but later variants employed semi-active radar homing to improve their effectiveness against high-performance and low-flying targets.
A possible solution for this problem was to use two radars, one for tracking the target and another for guiding the missile, but this drove up implementation costs.
Beam riding guidance based systems became more common again in the 1980s and 90s with the introduction of low-cost and highly portable laser designators.
Due to the shorter wavelengths used, a laser beam can be projected with a much narrower angular resolution than a radar beam while not requiring a significant increase in the size of the projector's aperture when compared to other optical devices being used by a typical guidance system for precision-guided munitions.
Because of this, it is possible to spatially encode additional information in a beam using digital or electro-optical means, which has a number of advantages.
Examples include ADATS, the Starstreak, the RBS 70, Russian 9K121 Vikhr and 9M119 Svir, Ukrainian Skif and Stuhna-P ATGMs.