# Antennas Questions and Answers – Frequency Independent Antenna – Rumsey Principle

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This set of Antennas Multiple Choice Questions & Answers (MCQs) focuses on “Frequency Independent Antenna – Rumsey Principle”.

1. Which of the following is Rumsey’s principle?
a) The impedance & pattern of antenna is frequency independent if antennasize is specified in terms of angle
b) The impedance & pattern of antenna is frequency dependent if antennasize is specified in terms of angle
c) The impedance & pattern of antenna is frequency dependent if antennasize is specified in terms of radiated power
d) The impedance & pattern of antenna is frequency dependent if antennasize is variable

Explanation: The frequency independent antennas are fixed in size and operate over wide bandwidth with constant impedance, polarization and pattern. Rumsey’s principle states that the impedance & pattern of antenna is frequency independent if antennasize is specified in terms of angle.

2. Rumsey’s principle is related to which type of antennas?
a) Frequency independent antennas
b) Frequency dependent antennas
c) Reflector antennas
d) Both Frequency independent and independent antennas

Explanation: Rumsey’s principle is applicable to the frequency independent antennas where the antenna size is specified in terms of angle and thus making the impedance and pattern independent of frequency.

3. Which of the following is truefor a frequency independent antenna?
a) Dimensions of antenna are specified in terms of angles
b) Dimensions of antenna are specified in terms of varying wavelengths
c) The antennas have variable impedance, pattern over operating wide band frequency
d) It does not follow Rumsey’s principle

Explanation: Rumsey’s principle states that the impedance & pattern of antenna is frequency independent if antennasize is specified in terms of angle. The Rumsey’s principle is applicable for the frequency independent antennas.The frequency independent antennas are fixed in size and operate over wide bandwidth with constant impedance, polarization and pattern.

4. The impedance and pattern are frequency independent if antenna shape is specified in terms of angle.
a) True
b) False

Explanation: Rumsey’s principle is the working principle of the frequency independent antennas. According to it the impedance & pattern of antenna is frequency independent if antenna size is specified in terms of angle. The antennas have fixed size and operate over a wide bandwidth having constant impedance and polarization.

5. Which of the following property doesn’t meet a true frequency independent antenna?
a) Fixed physical size
b) Constant impedance, pattern
c) Operates over wide bandwidth
d) Variable physical size

Explanation: Rumsey’s principle is used for the frequency independent antenna. A true frequency independent antenna must have a fixed physical size and operates on instantaneous basics over a wide bandwidth at a constant impedance, pattern.

6. Impedance of self-complementary antenna is ____
a) Zo/2
b) Zo/4
c) Zo
d) 2Zo

Explanation: The self complementary antennas have constant impedance which is half of their intrinsic impedance at all frequencies. These have a metal area congruent to open area. Impedance of self-complementary antenna = Zo/2.

7. Which of the following principle is mainly used in frequency independent antennas?
a) Rumsey’s principle
b) Fabry perot
c) Brewster law
d) Archimedes principle

Explanation: Rumsey’s principle is used in the frequency independent antennas states that the impedance & pattern of antenna is frequency independent if antennasize is specified in terms of angle. Fabry perot is used with optical waves where rays are passed only when they are in resonance. Brewster law gives the relation to maximum polarization of light.

8. Which of the following does not belongs to frequency independent antenna?
a) Spiral antenna
b) Log periodic antenna
c) Helical antenna
d) Parabolic antenna

Explanation: Parabolic antenna is a reflector antenna. Spiral, log periodic,helical antenna are examples of frequency independent antennas. A true frequency independent antenna must have a fixed physical size and operates on instantaneous basics over a wide bandwidth at a constant impedance, pattern.

9. Constant impedance of a self complementary antenna is Zo/4.
a) True
b) False

Explanation: The self complementary antennas have constant impedance which is half of their intrinsic impedance at all frequencies. These have a metal area congruent to open area. Impedance of self-complementary antenna = Zo/2.

10. Value of self complementary antenna when Zo=120π?
a) 120π
b) 60π
c) 240π
d) 30π

Explanation: One of the properties of the self-complementary antennas is constant impedance. Its impedance is half of the intrinsic impedance at all frequencies. Impedance of self-complementary antenna = $$\frac{Z_o}{2} = 60π.$$ 