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What is Terrestrial Microwave ? transmission systems consisting of at least two radio transmitter/receivers (transceivers) connected to high gain antennas (directional antennas which concentrate electromagnetic or radio wave energy in narrow beams) focused in pairs on each other. The operation is point-to-point-communications are established between two and only two antennas with line-of-sight visibility. This can be contrasted to point-to- multipoint systems like broadcast radio or television.

How Terrestrial Microwave Transfer and Receive Data Terrestrial microwave communication employs Earth-based transmitters and receivers to transfer and receive data. The frequencies used are in the low-gigahertz range, which limits all communications to line-of- sight. Example of terrestrial microwave equipment - telephone relay towers, which are placed every few miles to relay telephone signals cross country.

Antenna That Use to Transfer Data Microwave transmissions typically use a parabolic antenna that produces a narrow, highly directional signal. A similar antenna at the receiving site is sensitive to signals only within a narrow focus. Because the transmitter and receiver are highly focused, they must be adjusted carefully so that the transmitted signal is aligned with the receiver.

An Antenna is : An An effective interface between the radio and free space: Radio Antenna Free space a For Terrestrial Communications, antennas must be directional: Radio

G a (dBi) = 10 log 10  [ 4  A a /    Where: G a = Antenna Directive Gain (Catalog spec)  = Aperture Efficiency (50-55%) A a = Antenna Aperture Area  = Wavelength (speed of light / frequency) Formula Parabolic Antenna Directive Gain

Typical Parabolic Antenna Gain in dBi Antenna Diameter Frequency

Standard Parabolic Antenna Basic Antenna Comprised of –Reflector –Feed Assembly –Mount

Terrestrial Microwave Antennas for Point-To-Point Communication Terrestrial microwave antennas generate a beam of RF signal to communicate between two locations. Point-To-Point communication depends upon a clear line of sight between two microwave antennas. Obstructions, such as buildings, trees or terrain interfere with the signal. Depending upon the location, usage and frequency, different types can be utilized. We will address the basic characteristics of these various types…

The Use of Microwave Link A microwave link frequently is used to transmit signals in instances in which it would be impractical to run cables. If you need to connect two networks separated by a public road, for example, you might find that regulations restrict you from running cables above or below the road. In such a case, a microwave link is an ideal solution.

Ability To Connect With Other Devices Some LANs operate at microwave frequencies at low power and use unidirectional transmitters and receivers. Network hubs can be placed strategically throughout an organization, and workstations can be mobile or fixed. This approach is one way to enable mobile workstations in an office setting.

Frequencies That Use By Terrestrial Microwave In many cases, terrestrial microwave uses licensed frequencies. A license must be obtained from the FCC, and equipment must be installed and maintained by licensed technicians.

Frequencies That Use By Terrestrial Microwave Terrestrial microwave systems operate in the low- gigahertz range, typically at 4-6 GHz and GHz, and costs are highly variable depending on requirements. Long-distance microwave systems can be quite expensive but might be less costly than alternatives. (A leased telephone circuit, for example, represents a costly monthly expense.) When line-of-sight transmission is possible, a microwave link is a one-time expense that can offer greater bandwidth than a leased circuit.

Advantages of Terrestrial Microwave over Satellite Lower cost –Avoid exorbitant costs of leasing satellites (unless satellites are already owned by the customer) Reduced latency –Video is delivered with minimal delay. Satellite signals must travel significantly further with an average delay of 250 milliseconds for signals to travel to a geo- satellite and return to earth (this excludes video processing delay).

Advantages of Terrestrial Microwave over Satellite Increased Flexibility –BMS terrestrial systems are easily reconfigurable for different power levels and frequencies. –BMS terrestrial systems are mobile and easily deployed wherever coverage is needed. Multiple satellites may need to be utilized for all the required coverage areas. –Video can be captured using light weight, mobile equipment in difficult-to-reach areas. Video can also be captured by moving aircraft, ships, and vehicles. –Aircraft with BMS digital microwave for line-of-sight (LOS) communications can also be equipped with a satellite tracking antenna for beyond-line-of-sight (BLOS) satellite communications when needed.

Advantages of Terrestrial Microwave over Satellite Reduced Size & Weight –The RF link operates over a shorter distance and requires less power than a satellite equivalent. Lower power means less weight, smaller size and reduced power consumption. –Ground-based systems can use a tracking antenna for higher gain. Higher antenna gain results in lower transmit power requirements. This is less practical for satellite mounted antennas.