This set of Basic Analog Communications Questions and Answers focuses on “Practical Aspects of Sampling”.
1. A Marconi antenna has length equal to ________
Explanation: Marconi antenna is like a vertical wire having length one fourth of the working wavelength. It requires a ground plane with very good conductivity.
2. An antenna can be matched to a feed line by using an LC network only.
Explanation: An antenna can be matched to a feed line by using an LC network. But it can also be matched to feed line by a loading coil.
3. An array with one driven element, a reflector, and one or more directors is called ________
Explanation: A Yagi-Uda antenna is a directional antenna consisting of many parallel elements in a line. It consists of a single driven element which is connected to the transmitter or receiver with a transmission line, and also contains parasitic elements which are not connected to the transmitter or receiver.
4. The energy picked up by a parabolic antenna is concentrated at the ________
c) left corner
Explanation: Energy picked up by a parabolic antenna is concentrated at the focus.
5. Antennas are often tested in ________
a) an RF reflective chamber
b) a vacuum chamber
c) an anechoic chamber
d) an echo chamber
Explanation: An antenna is basically a transducer that converts radio frequency fields into alternating current or vice versa. They can be used for both transmission and reception of radio signals. They are often tested in an anechoic chamber.
6. Which one of the following consists of non-resonant antennas?
a) folded dipole
b) end-fire array
c) rhombic antenna
d) broadside array
Explanation: Non-resonant antennas are like non-resonant transmission lines. Non-resonant transmission lines do not have standing waves. Hence they do not have any reflected wave and they have only forward travelling wave.
7. Which one of the following is very useful as a multiband HF receiving antenna?
a) folded dipole
b) log periodic
c) conical horn
d) square loop
Explanation: A log periodic antenna is a multi-element, directional, antenna designed to operate over a wide band of frequencies.
8. Which among the following is not a reason for the use of antenna coupler?
a) To make the antenna look resistive
b) To provide the output amplifier with correct load impedance
c) To discriminate against harmonics
d) To prevent re-radiation of the local oscillator
Explanation: Antenna coupler is a device connected between a radio transmitter or receiver and its antenna to improve power transfer between them. Antenna coupler is never used to prevent re-radiation of the local oscillator.
9. Which of the following term is not applied to the Yagi-Uda array?
a) folded dipole
b) high gain
c) good bandwidth
d) high reception of signals
Explanation: A Yagi-Uda antenna is a directional antenna consisting of many parallel elements in a line. It consists of a single driven element and also contains parasitic elements.
10. Why top loading is used with an antenna?
a) to increase its effective height
b) to increase its beamwidth
c) to increase its bandwidth
d) to increase its input capacitance
Explanation: When the length of the antenna is shorter than a quarter wavelength ( ʎ⁄4), top loading is used to increase its effective height.
Sanfoundry Global Education & Learning Series – Analog Communications.
To practice basic questions and answers on all areas of Analog Communications, here is complete set of 1000+ Multiple Choice Questions and Answers.