Communication Systems & RF Flashcards

What is the impedance of a standard coaxial cable commonly used in RF systems?

Answer: 50 ohms

50-ohm coaxial cable is the standard for RF and microwave systems, balancing power handling and signal loss.

What type of antenna radiates equally in all horizontal directions?

Answer: Omnidirectional antenna

An omnidirectional antenna radiates and receives signals equally in all horizontal directions, making it ideal for general coverage.

What does the decibel (dB) measure in RF systems?

Answer: A logarithmic ratio between two power levels

The decibel expresses the ratio between two power levels on a logarithmic scale, making it easier to describe large gain or loss values.

In a PLL (Phase-Locked Loop) frequency synthesizer, what component compares the reference and feedback frequencies?

Answer: Phase detector

The phase detector compares the reference oscillator frequency with the divided VCO output to generate an error signal for frequency correction.

Which multiplexing method assigns each user a dedicated time slot in a shared channel?

Answer: TDMA

Time Division Multiple Access (TDMA) assigns each user a specific time slot within a repeating frame, allowing multiple users to share the same frequency.

What is the primary cause of multipath fading in RF communication systems?

Answer: Multiple signal reflections arriving at the receiver with different delays

Multipath fading occurs when reflected copies of a signal arrive at the receiver at slightly different times, causing constructive or destructive interference.

What is the purpose of an RF circulator in a communication system?

Answer: To route RF energy from one port to the next in a single direction

An RF circulator routes signals from port 1 to port 2, port 2 to port 3, and port 3 to port 1, allowing a single antenna to be shared by a transmitter and receiver.