Terrestrial Microwave TK2133 A103418 Lee Hau Sem A103411 Lai Horng Meau

1. Terrestrial Microwave TK2133 A103418 Lee Hau Sem A103411 Lai Horng Meau

2. 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.

3. 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.

4. 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.

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

6. Formula Parabolic AntennaDirective Gain Ga (dBi) = 10 log10h [ 4 p Aa / l2 ] Where: Ga = Antenna Directive Gain (Catalog spec) h = Aperture Efficiency (50-55%) Aa = Antenna Aperture Area l= Wavelength (speed of light / frequency)

7. Typical ParabolicAntenna Gain in dBi Antenna Diameter Frequency

8. Standard Parabolic Antenna • Basic Antenna • Comprised of • Reflector • Feed Assembly • Mount

9. 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…

10. 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.

11. 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.

12. 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.

13. Frequencies That Use By Terrestrial Microwave • Terrestrial microwave systems operate in the low-gigahertz range, typically at 4-6 GHz and 21-23 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.

14. 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).

15. 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.

16. 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.