ESAT RHM 2 Part 2 101-200

101. It is described in terms of luminous flux density in lumens per unit area.

102. It is also known as radiant flux. It measures the rate at which electromagnetic waves transfer light energy.

103. It is the decrease in the amount of light reaching the end of the fiber.

104. It is a form of energy that is moved by wave motion.

105. SCIENTIFIC EXPERIMENTS seem to show that light is composed of tiny particles, while other experiments indicate that light is made up of waves. Today, physicists have come to accept a theory concerning light that is a combination of ___________.

106. Is the ratio of velocity of propagation of a light ray in free space to the velocity of propagation of light ray in a given material.

107. It is the reflection from a perfectly smooth surface.

108. It states that semi-rough surface will reflect as if it were a smooth surface whenever the cosine of the angle of incidence is greater than "λ/8d"

109. An earth station for use with a geostationary satellite has a dish antenna which sees a sky temperature of 25 K. It is connected to the receiver with a feedline having 1 dB loss. The receiver equivalent noise temperature is 15 K. Calculate the noise temperature for the system.

110. For radio signals, the skip distance is determined by the:

111. Skip distance is the:

112. The skip distance of a sky wave will be greatest when the:

113. The wavelength of operation in fiber optics is between _____.

114. The substance through which a wave travels from one point to the next. Air, water, wood, etc., are examples of this.

115. The portion of a sine wave below the reference line.

116. Objects that either reflect or diffuse light that falls upon them.

117. It is also known as series tee. It is the electrical equivalent of connecting the arm in series.

118. These are used if change in polarization is needed. The length of twist is twice the wavelength.

119. These are thin, flat metal strips, much less than a wavelength in thickness and with low conductivity that are located in the cross-section of the inside walls of the waveguide.

120. When the sun is the primary body and is in farthest point.

121. Also known as the line of apsides. The line joining the perigee and apogee through the center of the Earth.

122. It has an apogee and perigee that have large differences.

123. It is the dBm referenced to a zerotransmission level point.

124. It is the process used to improve a basic telephone channel, wherein the attenuation and delay characteristics of a circuit are artificially altered to meet limits prescribed by the line conditioning requirements.

125. It is a signal returned to the talker after making one or more round trips between the talker and a distant reflection point.

126. It is the minimum angle of incidence at which light ray may strike the interface of two media and result in an angle or refraction of 90 degrees.

127. Is produced after rotating the acceptance angle around the fiber axis.

128. The light travels only in one path, and its core has smaller diameter.

129. What happens to light rays when they encounter any substance?

130. It is the wave that moves from the source to the object.

131. In the Radio Frequency (RF) spectrum, which is the range of UWB?

132. It states that the angle of incidence is equal to the angle of reflection.

133. It states that every point on a given spherical wavefront may be considered as a secondary point source of electromagnetic waves from which other secondary waves are radiated outward.

134. It is when two waves are in phase with each other, they form an addition in amplitude.

135. It is the tendency of the sun to have a greyish-black blemishes, seemingly at random times and at random places, on its fiery surface.

136. What effect does the D region of the ionosphere have on lower frequency HF signals in the daytime?

137. Two or more parts of the radio wave follow different paths during propagation and this may result in phase differences at the receiver. This "change" at the receiver is called:

138. When a transmitted radio signal reaches a station by a one-hop and two-hop skip path, small changes in the ionosphere can cause:

139. The point on a graph where the vertical and horizontal axes cross each other.

140. A cellular telephone system uses a 12-cell repeating pattern. There are 120 cells in the system and 20,000 subscribers. Each subscriber uses the phone on average 30 minutes per day, but on average 10 of those minutes are used during the peak hour. Calculate: the average and peak traffic in Erlangs for the whole system.

141. Another name for the REFERENCE LINE.

142. A triangular-shaped glass that refracts and disperses light waves into component wavelengths.

143. It is a device that reduces the signal strength as the microwave signals enter the waveguide.

144. It is also known as hot-carrier diode which replace the point-contact diode.

145. The power loss of an optical fiber cable is usually expressed in decibels per kilometer (dB/km). If the signal at the beginning of a cable with 0.3 dB/km rated loss has a power of 10 mW, what is the signal power (in mW) 9 km away?

146. It is also known as snap-off varactor diode, which is made with gallium arsenide or silicon.

147. It is the angle between the equatorial plane of the Earth and the orbital plane of the satellite.

148. It is a point on the circular orbit where the satellite crosses the equator and its move from north to south.

149. It is an orbit with a circular shape and has no inclination, thus it is in line with equator.

150. It is the result of sustained oscillations due to positive feedback in the telephone amplifiers or amplifying circuits.

151. Is the method of providing high-speed data transmission on twisted-pair telephone loops by using high-frequency carrier.

152. It is a device used to originate and terminate calls, and to transmit and receive signals into and out of the telephone network.

153. It is the graphical representation of the value of the refractive index across the fiber.

154. The index of refraction of the core is not constant, instead it varies smoothly and continuously over the diameter of the core.

155. Impurities in the fiber absorb the light and convert it to heat.

156. It describe how light energy is transmitted along an optical fiber.

157. Meridional rays can be classified as bound or unbound rays. This ray remain in the core and propagate along the axis of the fiber also propagate through the fiber by total internal reflection.

158. The index of refraction of the cladding material is _______ that of the core material.

159. It is the propagation mode wherein the radio waves are radiated from the transmitting antenna in a direction that produces a large angle with reference to the Earth.

160. It is a region directly above the troposphere where no weather is seen but circulation does occur.

161. It is the upper portion of the E Layer. It is a thin layer of very high ionization density, sometimes making an appearance with the E layer. It is caused by solar flares and sunspot activity.

162. A group of 20 servers carry a traffic of 10 Erlangs. If the average duration of a call is three minutes, calculate the number of calls put through by the group as a whole is one hour per period.

163. On the VHF and UHF bands, polarization of the receiving antenna is very important in relation to the transmitting antenna, yet on HF bands it is relatively unimportant. Why is that so?

164. How does the bandwidth of a transmitted signal affect selective fading?

165. Reflection of a SSB transmission from the ionosphere causes:

166. When they encounter any substance, they are either transmitted, refracted, reflected, or absorbed.

167. It is the basic optical material property that measures the speed of light in an optical medium.

168. Electromagnetic frequencies that fall between 3 kilohertz and 300 gigahertz and are used for radio communications.

169. The object that responds to a wave or disturbance. Same as detector.

170. The effective isotropic radiated power measured at the focal point of a gain antenna is 64 watts, what is the gain of the antenna in dBi if the power produced by the transmitter connected to the gain antenna via a lossless transmission line is 250 mW?

171. The wave that reflects back from a medium.

172. It is also known as Esaki diode, which is also a negative resistance diode which has the ability to add energy and permit amplification and oscillation.

173. Is a metal wrapped around the antenna aperture to eliminate side lobes which may cause interference to nearby microwave stations.

174. It is a single transmission path from transmitter to receiver.

175. Are those lines drawn on the surface of the Earth from the north pole to south pole.

176. It has a rotation period of 5 to 12 hours and remain in sight from an Earth station for 2 to 4 hours.

177. Is the most common gas used for satellite's jet thruster.

178. Are used to interconnect two telephone offices.

179. It is used to connect a local exchange and a tandem office.

180. Is a telephone call that was completed within a single local exchange.

181. It is the result of photons of light that are absorbed by the atoms of the glass core molecules.

182. It is due to the imperfections in the fiber that are formed during manufacturing process. When light strike these impurities they are diffracted, this is known as Rayleigh scattering loss.

183. It is predominantly caused by small bends and kinks in the fiber.

184. The material used for a buffer is a type of plastic. The buffer is elastic in nature and prevents ______.

185. Ray theory is also called as ________.

186. Mode theory is also called as _______.

187. It is the highest frequency at a given ionization density that will be returned down to the Earth when beamed vertically upward.

188. It is the highest angle of radiation that will return the wave to the Earth at a given density of ionization in the layer for the frequency or wavelength.

189. It is the frequency that provides the most consistent communication. Operating at a frequency of 85% of the MUF.

190. How long is an average sunspot cycle?

191. What is the solar-flux index?

192. Which two types of radiation from the sun influence propagation?

193. __________occurs because the mode propagation constant (β) is a function of the size of the fiber's core relative to the wavelength of operation.

194. The wave moving back to the sending end of a transmission line after reflection has occurred.

195. The multiple reflections of sound waves.

196. The name given to the end of a two wire transmission line that is connected to a source.

197. These are points in the microwave communications system where baseband signals may be reconfigured or where RF carriers are simply repeated or amplified.

198. It intercepts, amplifies and retransmit the signal and provides gain.

199. Occurs when the power that leaks out the back and sides of a transmit antenna interferes with the signal entering the input of a nearby receive antenna.

200. Is the process of adjusting the orbit of a geostationary satellite so that it appears to remain stationary above a point on the Earth.