17 Questions
What type of antenna can be described as an opened-out transmission line open-circuited at the far end and of resonant length?
Resonant antenna
In a resonant antenna, why is the length chosen to be a multiple of quarter-wavelengths?
To achieve resonance
What happens to the radiation at right angles from a full-wave dipole antenna?
It is zero
What is the direction of maximum radiation for a full-wave dipole antenna?
54° to the antenna
How does the length of an antenna affect its radiation pattern in free space?
Changes the shape of the lobes
What does it mean when the polarity of current on one half of an antenna is opposite to that on the other half?
Zero radiation at right angles
What does the term 'radiation resistance' refer to in the context of antennas?
The power that an antenna radiates into free space relative to the driving power supplied to the antenna.
How does the AC resistance of the transmission line impact the overall impedance and power delivered to the antenna?
AC resistance impacts the overall impedance that the antenna sees, which affects the power delivered to the antenna.
What is the purpose of a parallel-tuned circuit in radio communication systems?
To adjust the resonant frequency of the antenna for optimal radiation resistance and efficient operation.
How does the radiation resistance of an antenna change with different operating conditions?
The radiation resistance remains constant across different operating conditions.
What is the relationship between the current at the feed point of an antenna and its radiation resistance?
The radiation resistance increases as the current at the feed point increases.
If an antenna needs to be replaced, what is the most important consideration for the replacement antenna?
The radiation resistance of the replacement antenna.
What is the primary function of the radiation resistance in an antenna system?
To convert the current flowing at the feed point into radiated electromagnetic energy
Why is understanding the impact of radiation resistance crucial when designing or modifying antenna systems?
To optimize the antenna's performance in terms of signal quality, coverage, and overall system efficiency
What is the purpose of adjusting the values of capacitors and inductors in an antenna circuit?
To fine-tune the antenna's performance to meet specific requirements
What is the significance of the a.c. resistance in an antenna system?
It affects the antenna's ability to radiate electromagnetic energy efficiently
In a parallel-tuned circuit used in antenna systems, what is the purpose of the inductor and capacitor?
To adjust the resonant frequency of the circuit to the desired operating frequency
Test your knowledge on resonant antennas and dipole antennas. Learn about the characteristics of resonant transmission lines and the radiation patterns of wire radiators in free space.
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