Microwave Link details provided on the following areas; freedom from land aquisition, ease of communication over difficult terrain, bandwidth allocation, atmospheric effects, transmission paths, interference and costs.

Microwave Link

The maturity of radio frequency (RF) technology has permitted the use of a microwave link as the major trunk channel for long distance communication. The use of a microwave link has major advantages over cabling systems:

The acquisition of rights to lay cabling, repair cabling, and have permanent access to repeater stations is a major cost in the provision of cable communications. The use of radio links, that require only the acquisition of the transmitter/receiver station, removes this requirement. It also simplifies the maintenance and repair of the link.

Some terrains make cable laying extremely difficult and expensive, even if the land acquisition cost is negligible.

The use of a microwave link has a number of disadvantages that mainly arise from the use of free-space communication:

The competition for RF bandwidth from various competing users leads to very strict allocations of bandwidth. Unlike cabling systems, that can increase bandwidth by laying more cables, the radio frequency (RF) bandwidth allocation is finite and limited. In practise, bandwidth allocations of 50MHz in the carrier range 300MHz to 1GHz are typical.

The use of free-space communication results in susceptibility to weather effects particularly rain.

Microwave communication requires line-of-sight, point-to-point communication. The frequency of repeater stations is determined by the terrain. Care must be taken in the system design to ensure freedom from obstacles. In addition, links must be kept free of future constructions that could obstruct the link.

The microwave system is open to RF interference.

The cost of design, implementation and maintenance of microwave links is high. Many countries are not well equipped with good technical resources to provide efficient and continuous operation.

The modern urban environment presents a particular challenge, in that bandwidth allocation, RF interference, link obstruction and atmospheric pollution place maximum constraints on the system simultaneously. However, urban environments also have the highest land acquisition values too. Many modern cities have found it cost effective to build a single, very high tower to house an entire city's trunk communication microwave dishes. These towers are now a common feature of the modern urban landscape.

As the demand for bandwidth increases, microwave links will become increasingly unable to deliver. The use of increased carrier frequencies in the millimetre wave region would be advantageous. However, for technical reasons, no efficient method of producing large quantities of millimetre power have been found. This is a necessity, given the increase in atmospheric attenuation at millimetre wave frequencies.