NTC - Amateur Class A Examination. Below are elements 9

1.	Why are guy wires cut in different lengths?
Ans: To prevent re-radiation of signals

2.	The angles created by comparing the half power points on the main radiation lobe to its maximum power points of an antenna is known as
Ans: Beamwidth

3.       What is the power measurement level of an antenna considered as half powr points on the main radiation lobe?
Ans: 3dB

4.	What is the term used when referring to the space orientation of the electromagnetic wave being radiated by a transmitting system?
Ans: Polarization

5.	The ratio of the power radiated by the antenna to the square of the current at the feedpoint is
Ans: Gain of the antenna 

6.	Waveguide equivalents of tuned transmission lines is
Ans: Balanced reactors

7.	An example of a non resonant antenna
Ans: Log periodic

8. A device used to connect antenna to the output tank of a transmitter in order to prevent the dc supply from reaching the antenna
Ans: An antenna coupler

9.	Transmission lines normally used for frequencies above 186Hz
Ans: parallel wire line

10.	What is the wavelength if the frequency used is 300MHz?
Ans: 1m

11.	What is the quarter wavelength of 150MHz
Ans: 0.5m

12.	What is the approximate height of the geostationary satellites above the earths surface?
Ans: 36,000km

13.	What is the other name in directing in propagation of radio waves?
Ans: Super refraction 
 
14.	What is the speed of electromagnetic waves in free space?
Ans: 3x10 raised to 8 m/s (300,000,000 m/s)

15.	Gain of an antenna is a measurement of ratio of output power in an antenna in a certain direction compared to that of
 Ans: Hybrid antenna 

16.	The unit of measurement of antenna field strength is
Ans: electromagnetic line of force 

17.	Antennas which are grounded are know as
Ans: Marconi antennas

18.     In order to effectively lengthen a Marconi type antenna top loading is
 Ans: placing inductance in series with the antenna

19.What is the element of an antenna array that is not directly connected to the output of the transmitter?
Ans: Antenna rod 

20. A type of antenna consisting of a number of dipoles of different length and spacing, fed from a two wire line is transposed between each adjacent pair of dipoles
Ans: Rhombic

21.	The equivalent of transmission line in higher or microwave frequencies
Ans: Coaxial cables

22.	The bending of radio waves as they pass over the upper edge of a hill or mountain is know as
Ans: Knife edge refraction 

23.	For line of sight propagation, which frequency band is more adaptable?
Ans: VHF

24.	What type of modulation is largely contained in static and lightning radio waves?
Ans: AM

25.	Mobile antennas are of two types, quarter wave ground plane and half wave type. They are both
Ans: coaxial

26.	What is the unit of field intensity?
Ans: Volts/m

27.	The ratio of the voltage to the current along infinite line terminated in its own 
Ans: Characteristic impedance

28.	Circuit or device that permits transmit and receive on one antenna
Ans: Duplexer

29.	A circuit device that permits two different transmitters to use one antenna
Ans: Diplexer

30.	On what tv channel does the 2nd harmonic of a 27MHz transmitter fall?
Ans: Ch2

31.	A plot of the relative strength or intensity of the antenna radiation as a function of the orientation in a given placed is called
Ans: radiation pattern

32.	ratio of the power radiated by an antenna to the square of the current
Ans: Gain of Antenna 

33.	The product of power fed to an antenna to its gain
Ans: Output power 

34.	The ratio of current or voltage delivered to the antenna to the reflected back down the transmission line is know as
Ans: Reflection coefficient 

35.	The most ideal voltage standing wave ratio is
Ans: 1.2:1 

36.	What instrument is used to measure the received strength of a radio signal?
Ans: SWR Meter 

37.	The unit used in indicating the difference between field strength of the fundamental radiation and the harmonic radiation
Ans: decibels

38.	What is the effective radiated power of a transmitter fed with 1000W passing along a transmission line with a loss of 50W and an antenna gain of 3?
Ans: 3000W

39.	What power is fed to an antenna if the surge impedance of the transmission line is 500 Ohms and the line current is 3 Amperes?
Ans: 4500 watts or 4.5KW

40.	One of these is classified as a parasitic antenna element
Ans: reflector

41.	Characteristic of an antenna referring to its capability of beaming energy in a narrow range of directions
Ans: Directivity

42.	What is the unit of magnetic field intensity?
Ans: Volts per meter

43.	What is the parameter that compares the concentration of power in the given antenna to that of  some reference antenna
Ans: Gain of the antenna

44.	When the electric field line is parallel to the earths surface the polarization is said to be
Ans: horizontal

45.	What is the resistance of free space?
Ans: 377 Ohms

46.	The gain in the direction of one of the major lobes of the radiation pattern is known as
Ans: Directive gain

47.	Antenna gains are measured with reference to
Ans: Isotropic radiator

48.	When the electric field lines in a plane are perpendicular to the earths surface, the polarization is said to be
Ans: Vertical