The GB3FNM Beacons

The group also hosts microwave beacons on behalf of the UK Microwave Group. One beacon is currently active:

Beacon descriptions

The active beacons nominally provide omni-directional coverage subject to variations in the antenna pattern. Where possible the antennas are oriented to favour directions up-country and towards the continent.   The beacons provide a useful resource for propagation monitoring and enable microwave operators to check their receiving equipment.   The equipment consists of indoor units (IDU) which include the power supplies, keyers, stable frequency references and intermediate or final frequency generation. The intermediate frequency for the 5.7 GHz beacon and power are supplied to the corresponding mast mounted Outdoor Unit (ODU) via coaxial cables. Since early 2010, the OCXOs have been locked to the 5MHz reference used for the GB3FN and GB3FX repeaters, to give improved frequency stability.   All the beacons use slotted waveguide antennas which produce a polar diagram in the form of a four leaf clover with approximately 10dB of gain in the main pair of lobes (180 degrees apart) and 6dB gain in the minor lobes (at right angles to the main lobes). The nulls are at approximately 0dB. The main 5.7 GHz beacon lobes are aimed ENE/WSW while the minor lobes are at 90 degrees to these, i.e. NNW/SSE. The 5.7GHz antenna is housed in a separate radome connected to the 5.7GHz ODU by a short length of low loss cable.