# Microwave Engineering Questions and Answers – Co-axial Lines

«
»

This set of Microwave Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Co-axial Lines”.

1. What are the modes of propagation that a co axial line supports?
a) TM, TE mode
b) TM, TE, TEM mode
c) TM, TEM mode
d) TE, TEM mode

Explanation: Certain propagating media support specific modes of propagation. Coaxial cables support all the three modes of propagation. They are TM, TE, and TEM modes.

2. The dominant waveguide mode of a co axial line is:
a) TE11 mode
b) TE01 mode
c) TM01 mode
d) TEM mode

Explanation: Co-axial cable many modes of propagation. Among those supported modes of propagation, the dominant mode, the mode with lowest propagating wavelength is TE11 mode.

3. In a co axial line with inner and outer diameters of 0.0645 and 0.0215 inches and a Teflon di electric with ∈r=2.2. The highest usable frequency before the TE11 waveguide mode starts to propagate is:
a) 16.8 GHz
b) 117.7 GHz
c) 15.3 GHz
d) 8.4 GHz

Explanation: Before the wave propagation starts, the unstable frequency is given by the expression Ck/2π√∈. Here, C is the velocity of light. Substituting the given values in the above expression, the frequency is 16.8 GHz.
Note: Join free Sanfoundry classes at Telegram or Youtube

4. If a wave guide has he inner and outer conductor diameters of 0.0645 and 0.0215 inches respectively for a co axial lines then the cut off wave number is:
a) 298
b) 300
c) 285
d) 123

Explanation: The cutoff wave number for wave propagation is given by 2/ (a + b). a, b are the inner and outer diameter respectively. Substituting in the above expression, cut off wave number is 298.

5. The commercially used co axial cable and connectors used has a characteristic impedance is:
a) 50Ω
b) 100Ω
c) 33.34Ω
d) 66.6Ω

Explanation: All commercial manufacturer s of coaxial cables and connectors have set a standard for all the manufactured products. The standard value is 50 Ω.

6. In television systems the characteristic impedance of the cables used is:
a) 75Ω
b) 150Ω
c) 100Ω
d) 50Ω

Explanation: All cable manufacturers of the television system follow a set of standards. As per these set standards, the characteristic impedance of the line is 75 Ω.

7. SWR standing wave ratio has to be ________for co axial connector.
a) Low
b) High
c) Infinite
d) Cannot be calculated

Explanation: Higher the value of the standing wave ratio more is the reflection which implies mismatch. Hence, standing wave ratio has to be low.

8. What are the connectors used in pairs called?
a) Jack and plug
b) Male and female connectors
c) Both the mentioned
d) None of the mentioned

Explanation: There are certain special connectors that can be used to connect two devices operating devices. These special connectors are to be used in pairs and are with both the names.

9. The frequency range for N type co axial connector is:
a) 8-12 GHz
b) 11-18 GHz
c) 14-20 GHz
d) 2-8 GHz

Explanation: N type connectors are coaxial connectors used at microwave frequency range. These type of connectors can be used in the frequency range of 11-18 Hz.

10. The frequency range of SMA co-axial connector used most commonly is:
a) 18-25 GHz
b) 25-50 GHz
c) 11-18 GHz
d) 8-12 GHz