Microwave

Microwave systems and its applications

Microwaves are radio waves in wavelengths between 1 mm to 30cm long and for some books say 1 m to 1 mm and operate at a frequency of 300 MHz to 300 GHz. Microwave radio systems are basically used for long-distance transmission. With microwave systems, we could eliminate wires for transmission and instead we could transmit radio waves. Microwaves could be used on rough terrains and could penetrate through smoke, rains and adverse conditions. These frequencies are useful for terrestrial and satellite communication systems, both fixed and mobile.  In the case of point-to-point radio links, antennas are placed on a tower or other tall structure at sufficient height to provide a direct, unobstructed line-of-sight (LOS) path between the transmitter and receiver sites. In the case of mobile radio systems, a single tower provides point-to-multipoint coverage, which may include both LOS and non-LOS paths.  LOS microwave is used for both short- and long-haul telecommunications to complement wired media such as optical transmission systems. 

Today, technology has arisen to improved microwave systems. They are being used for Personal Communication Service and Cellular systems. Installations of microwaves systems are of easy nowadays than installing cables a mile long. PCS systems and cellular systems have installed microwave radio systems around the globe to further increase their range and performance. Some operators like police, fire department and emergency units use these microwave systems.

TV stations also use microwaves to facilitate with their wireless transmission. Now with their live feeds and remote locations sites, they could transmit video streams or data without a problem using small microwave antennas. There is also what we call satellite TVs. This TVs rely on microwave frequencies for video and audio transmission from their carriers. It uses microwave frequencies for transmission. Microwave communication via satellite provides a more reliable signal than longer, land−based radio waves. It also improves the reception of the picture. The DBS or direct broadcast satellite (shown in the picture below) provides the programming and selects channels to be broadcast to the customers.

Bandwidth and Realibility Issues

Bandwidth is costly and in need as consumers grows fast. Bandwidth may be bought but for a higher price but this would satisfy the users. Buying bandwidth would be used for the future and an increase on your capacity which means lesser traffic. Microwave systems are complex and require maintenance so it might also be a cut to the budget of buying bandwidth for users. Reliability is also a factor. Buying bandwidth is not just for capacity but also for reliability. But equipment should also be secured and reliable not just the bandwidth.

Microwave advantages:

§  Adapts to difficult terrain

§  Loss versus distance (D)  = Log D (not linear)

§  Flexible channelization

§  Relatively short installation time

§  Can be transportable

§  Cost usually less than cable

§  No “back-hoe” fading

A microwave link can transmit Gb of data without dropping a single bit (or packet when a data transmission uses packetized information). On copper wire, noise is always present. Thermal noise causes a continuous hum, white noise, and the like. A microwave path can be so clear that if no one is talking or sending data, the line is perfectly silent. This is difficult for the average layperson to understand.

Microwave Disadvantage:

§  Paths could be blocked by buildings

§  Spectral congestion

§  Interception possible

§  Possible regulatory delays

§  Sites could be difficult to maintain

§  Towers need periodic maintenance

§  Atmospheric fading

Reference:

http://www.eogogics.com/talkgogics/tutorials/microwave-line-of-sight-systems

http://electronics.howstuffworks.com/satellite-tv2.htm