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

A corporate feed network distributes equal amplitude signals to all array elements via equal path lengths, ensuring uniform illumination and consistent phase across the entire array aperture.

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 feed networks require less transmission line material but cause beam squint (beam direction shift) as frequency changes because elements experience different electrical path lengths.

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

A diplexer uses bandpass and bandstop filters to combine or separate two different frequency bands at a single antenna port, allowing one antenna to serve two bands.

Question 4

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

Accepted Answer

Horn antenna

Answer

Horn antennas are the most common prime focus feeds for parabolic reflectors due to their well-controlled illumination patterns, low spillover, and compatibility with standard waveguide connections.

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

A rat-race coupler is a 180° hybrid that combines or splits power with either 0° or 180° phase difference depending on which ports are used, making it useful in balanced mixers and antenna feed networks.

(CAD) Certified Antenna Designer Practice Test

(CAD) Certified Antenna Designer Practice Test

CAD CAD Antenna Designer Feed Networks and Impedance Matching 3