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
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