CAD CAD Antenna Designer Feed Networks and Impedance Matching 3

Question 1

What is the primary purpose of a corporate (parallel) feed network in a phased array antenna?

Accepted Answer

To distribute equal amplitude and phase to all array elements

Answer

To introduce progressive phase shifts for beam steering

Answer

To increase the impedance of each radiating element

Answer

To reduce the number of transmission line connections needed

Question 2

How does a series feed network for a linear array differ from a corporate feed network?

Accepted Answer

Series feeds use less transmission line but exhibit beam squint with frequency change

Answer

Series feeds provide inherently higher bandwidth than corporate feeds

Answer

Series feeds provide better inter-element isolation than corporate feeds

Answer

Series feeds can only be used with microstrip patch antennas

Question 3

What is the function of a diplexer in an antenna system?

Accepted Answer

To combine or separate two frequency bands through a single antenna port

Answer

To amplify two different frequency bands simultaneously

Answer

To convert a single-polarization antenna to dual-polarization operation

Answer

To match impedances between two antennas connected in parallel

Question 4

What type of feed antenna is most commonly used at the prime focus of a parabolic reflector?

Accepted Answer

Horn antenna

Answer

Microstrip patch antenna

Answer

Log-periodic antenna

Answer

Yagi-Uda antenna

Question 5

What is a rat-race coupler (ring hybrid) primarily used for in microwave feed networks?

Accepted Answer

To combine or split power with 0° or 180° phase difference between output ports

Answer

To combine or split power with a 90° phase difference between output ports

Answer

To provide wideband impedance transformation without reflections

Answer

To create high isolation between adjacent transmission line runs

Question 6

What is the main advantage of using a tapered transmission line section in an antenna feed network?

Accepted Answer

To achieve gradual impedance transformation with low reflections over a wide bandwidth

Answer

To reduce the physical footprint of the feed network on the substrate

Answer

To increase the power handling capability of the transmission line

Answer

To improve isolation between adjacent parallel feed lines

Question 7

In a traveling-wave series feed for a linear array, how are element spacing and feed line length coordinated?

Accepted Answer

Element spacing and feed line electrical length create a specific phase progression to form the beam

Answer

All elements receive maximum power with no inter-element phase progression

Answer

Power decreases exponentially from the first to the last element with no phase control

Answer

Only the first and last elements radiate while intermediate elements are terminated in matched loads