 antenna. It is provided by the antenna manufacturer and is used to secure the antenna firmly on the tower (or pole, etc.). Two aspects that are needed during the alignment and mounting phase are the azimuth and bearing, the former being the angle of the antenna relative to the ground and the latter the compass orientation. Weight of the Antenna This figure is handy when many antennas are being mounted on one pole/tower. Engineers should know the strength of the pole/tower before mounting the antennas. If it is a green-field site, the type of pole/tower can be suggested according to the size and/or number of antennas that need to be mounted on it. If it is an area of high wind speed, then the structure supporting the antennas should be stronger, SO that the antennas do not lose their alignment or fall down. Waveguide Minimising losses is one of the key aspects of microwave link design. Cables and waveguides also contribute to the losses. Hence cables and waveguides that give minimum resistance to the signal are used. Usually for frequencies below 2 GHz, coaxial cables are used and for frequencies above 2 GHz, waveguides are used. Coaxial cables are used because they give low losses and are economical. Generally, coaxial cables that are used are foam dielectric cables that are unpressurised, having diameters of 1/2, 7/8 and 5/8 inch. The smaller the diameter, the higher is the attenuation. If the feeder losses are critical, then air dielectric coaxial cables should be used as they have lower attenuation than the foam dielectric cables. Waveguides can be rectangular, circular and elliptical. Rectangular Waveguide These are most commonly used with oxygen-free, high conductivity copper. Some examples of these waveguides are: 3-5 GHz: WR-187 (loss: 0.07 dB/m) 6-7 GHz: WR-137 (loss: 0.114 dB/m) 10-11 GHz: WR-90 (loss: 0.217 dB/m) Usually, manufacturers specify the losses per metre or per inches. The losses are calculated for the whole length of the cable. Thus, microwave engineers should try to design the systems in su