Microwaves Part 1

Microwaves

are electromagnetic waves with frequencies ranging from 300MHz to 300GHz

Properties of Microwaves

propagate in a straight line

can be reflected by a conductive surface

Microwave Communication System

A form of electronic communication using microwaves to transmit and receive information signals

Microwave Link

Simplest form of a Microwave Communication System

Hop

two microwave terminals form a _____

Microwave Radio

point to point fixed digital link that operates in duplex mode

Duplex Mode

means each channel consists of a pair of frequencies for transmission and reception

Duplex Mode

sometimes called low band channels

T to R Spacing

spacing between 2 frequencies

Frequency Division Duplexer

transmit and receive frequencies are combined into one antenna

Duplexer

provides coupling for 2 signals

Digital Modem

RF Unit

Passive Parabolic Antenna

3 basic modules for icrowave radio terminal

Digital Modem

to interface with customer equipment

RF Unit

to up and down

Passive Parabolic Antenna

transmission and reception of signals

E1

basic digital channel

E1

has 30 voice channels and 64kbps

1 + 0 Config or Non protected

1 + 1 Config or protected

Basic Hardware Protection Config

1 + 1 Config or protected

also known as Monitored Hot Standby MHSB

Analog and Digital

Type of signal by nature

Long Haul

Short Haul

Type of signal by distance

Narrowband

Wideband

Type of Signal by capacity

Long Haul

frequencies greater than 15Ghz

Short Haul

uses lower frequencies to minimize attenuation

Narrowband

less than 3Ghz in frequency

Wideband

utilizes frequencies from 3 to 15 Ghz

Microwave Links

used for control and maintenance of power grids

Snell’s Law

angle of refraction is governed by

Abnormal Atmosphere

may result to diffraction loss as well as multipath fading and ducting

Effective Earth Radius

is the actual earth radius multiplied by k factor

Earth Bulge

earth radius corresponds to the flattening or bulging of earth

K factor

numerical figure that considers non ideal conditions

Cold/Dry Areas and High altitudes

These areas have a low k factor

Coastal Areas where humidity is high

These areas have a high k factor

Superstandard Refraction

also called super refraction

Superstandard Refraction

results from meteorological conditions and also from water vapor

Subtandard Refraction

occurs when the dielectric constant of the atmosphere increases with height

Inverse Beam Bending

tends to be deflected away from earth

Blackout Conditions

when G becomes zero

Ground Based Duct

very dense layer of air close to the ground with a thin layer on top of it

Elevated Duct

exists when atmosphere has thick layer in some height above ground

Ducting Probability

percentage of time when dN/dH is less than 100N/km

Evaporation, Advection, Temperature Inversion

causes for ducting

Equatorial Regions

most vulnerable to ducts