Subelement B: Transmitting Systems – 8 Key Topics – 8 Exam Questions— Topic 14: Pulse Forming Networks Modulation
Question 8-14B4
Element 8 (RADAR)The shape and duration of the high-voltage pulse delivered to the magnetron is established by:
Explanation
The high-voltage pulse delivered to a magnetron, especially in radar systems, is precisely shaped and timed by an **artificial delay line**, also known as a Pulse Forming Network (PFN). This network consists of a series of inductors and capacitors designed to store energy and then release it in a controlled, rectangular pulse. The specific inductance and capacitance values in the delay line determine its characteristic impedance and, crucially, the time it takes to discharge, which directly establishes the precise duration and desired shape of the high-energy output pulse for the magnetron.
* **A) An RC network in the keyer stage** primarily sets timing for trigger pulses, not the high-power pulse's shape or duration.
* **B) The duration of the modulator input trigger** initiates the discharge of the PFN but does not define the resulting high-power pulse's duration; the PFN does.
* **D) The time required to saturate the pulse transformer** refers to an undesirable limiting effect, not a controlled mechanism for establishing the intended pulse shape and duration.
Related Questions
8-14B2 Pulse transformers and pulse-forming networks are commonly used to shape the microwave energy burst RADAR transmitter. The switching devices most often used in such pulse-forming circuits are:8-14B3 The purpose of the pulse-forming network is to:8-14B5 Pulse-forming networks are usually composed of the following:8-14B6 An artificial transmission line is used for:8-15B1 The ferrite material in a circulator is used as a(an):