– A type of wireless communication is the microwave transmission.
– The technology concerning the transmission of the energy or the information through radio waves (microwaves to be particular) is called the microwave transmission.
– Microwaves are the waves whose wavelengths can be measured in few centimeters.
– The microwaves lie in the frequency range of 1 GHz to 30 GHz of the radio spectrum.
– The centimeter range corresponding to frequency range of the microwaves is from 1 cm to 30 cm.
– Microwave transmission find its major use in the field of unicast or point – to – point communication.
– This is because the antennas of convenient size can direct these waves in to thin beams because of their small wavelengths.
– Theses narrow beams then can be directed towards the antenna at the receiving end directly.
– With this some nearby microwave equipment can make use of the same frequencies without getting involved with the interference issues as it happens in the radio waves with lower frequencies.
– Microwave transmission has one more advantage to offer which is that the microwaves have very high capacity for carrying information because of their high frequency.
– The bandwidth of the microwaves is 30 times larger than those lying below it in the radio spectrum.
But with advantages there are disadvantages also.
– One disadvantage is that the microwave transmission is appropriate only for the LOS (line – of – sight) propagation.
– Thus, it is limited to a very short range of distance.
– It is not possible for the microwaves to go around the hills or trees as the frequencies lower than that can do.
– Therefore, the microwave transmission is used in the unicast communications on the earth’s surface.
Applications of Microwave Transmission
– For example, it is used in very deep space radio communication and satellite communication.
– Systems in sensors, radio astronomy, radio navigation systems and radars utilization the different parts of the microwaves.
– Terrestrial microwave radio broadcasting is another application of the microwave transmission.
– It relay links in communication networks.
– For example, it links BSC – MSC and BTS – BSC in case of the backbone carriers in the cellular networks.
Technology behind Microwave Transmission
– For directing the microwaves in to beams for unicast or radiolocation, the antenna used is a parabolic one.
– It consists of a parabolic reflector for achieving narrow beams.
– The reflector is kept larger than the radio wave’s wavelength.
– However, because of their shorter wavelength they allow dishes of reasonable size to be used for providing directional response both in the case of transmission and reception.
– One technology associated with the microwave transmission is the microwave radio delay.
– This technology is used for the transmission of the digital as well as the analog signals.
– These signals include computer data, telephone calls and television programs.
– In this technology two directional antennas are used one at the transmitting location and the second one at the reception.
– A fixed radio connection is formed between the two locations.
– The maximum distance between the two locations must not exceed 40 miles.
– Since the high frequencies are used, between the two stations a quasi – optical LOS is required.
– Also, there has to be no obstacles in the path of the transmission between two stations.
– Any obstacle in the path can lead to the attenuation of the signal.
– This attenuation is tolerable only in few cases.
While planning the radio links some important issues to be considered include:
– Curvature of the Earth
– Geography of that area
– Other reception issues.
Path profiles need to be produced for obtaining information about the Fresnel and the terrain that might affect the path of transmission. If there is a water body present in the path, it also has to be taken in to consideration since it can cause multipath distortion because of its reflective properties. A majority of the telephone traffic is carried by the microwave relay links.