Subelement A: RADAR Principles – 10 Key Topics – 10 Exam Questions – 8 Drawings— Topic 8: Components-2
Question 8-8A1
Element 8 (RADAR)The basic frequency determining element in a Gunn oscillator is:
Explanation
A Gunn oscillator utilizes a Gunn diode, which exhibits negative resistance at microwave frequencies. To sustain oscillations, this diode must be coupled to a resonant structure. The resonant cavity provides this structure, acting as an electromagnetic resonator that determines the specific frequency at which the oscillator will operate. Its physical dimensions, such as length and diameter, dictate the resonant frequency.
Therefore, changing the cavity's size or tuning it (e.g., with a screw) directly alters the output frequency.
A) The power supply voltage biases the diode and affects output power, but not the fundamental frequency.
B) The type of semiconductor (e.g., Gallium Arsenide) determines the diode's operational characteristics and frequency *range*, but not the specific, precise operating frequency.
D) Loading by a mixer is an external factor that might affect stability or power, but it doesn't determine the oscillator's inherent frequency.
Related Questions
8-7A5 Which is typical current for a silicon crystal used in a RADAR mixer or detector circuit?8-7A6 What component of a RADAR receiver is represented by block 47 in Fig. 8A1?8-8A2 Which of the following is not a method of analog-to-digital conversion?8-8A3 When comparing TTL and CMOS logic families, which of the following is true:8-8A4 The primary operating frequency of a reflex klystron is controlled by the: