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RF Transmission & Antenna Systems Flashcards

7 cards from real CBT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 RF Transmission & Antenna Systems flashcards as text

  1. In broadcast engineering, what does ERP stand for and what does it represent?

    Answer: Effective Radiated Power — transmitter power multiplied by antenna gain relative to a dipole

    ERP (Effective Radiated Power) is the product of the transmitter power fed to the antenna and the antenna's gain referenced to a half-wave dipole, representing the apparent power radiated in the maximum direction.

  2. What is the primary function of a circulator in a high-power broadcast transmitter output stage?

    Answer: To protect the transmitter PA from damage caused by high reflected power

    A circulator directs reflected power (from antenna mismatches) into a dummy load, protecting the transmitter's final amplifier stage from potentially damaging high VSWR conditions.

  3. How does antenna height above average terrain (HAAT) affect FM broadcast coverage?

    Answer: Higher HAAT increases coverage by extending the radio horizon

    FM propagation is essentially line-of-sight, so greater HAAT extends the radio horizon and increases the geographic coverage area significantly.

  4. What is the purpose of pressurizing a coaxial transmission line with dry nitrogen?

    Answer: To prevent moisture ingress that would increase line losses and cause arcing

    Dry nitrogen pressurization keeps moisture out of the transmission line, preventing increased dielectric losses, corrosion, and potential arcing at high power levels.

  5. A broadcast antenna has a horizontal radiation pattern (HRP) that is not perfectly omnidirectional. What is this called?

    Answer: Directional antenna pattern

    An antenna that radiates unequally in different horizontal directions is classified as a directional antenna, and its pattern must be FCC-licensed to protect co-channel and adjacent channel stations.

  6. What is the typical power loss per 100 feet for 1-5/8 inch Heliax coaxial cable at 100 MHz?

    Answer: Approximately 0.5 dB per 100 feet

    1-5/8 inch Heliax (Andrew LDF7-50A type) exhibits approximately 0.5 dB per 100 feet at 100 MHz, making it well-suited for long tower runs in FM broadcast applications.

  7. What FCC rule governs the maximum allowable antenna height and power for full-power FM broadcast stations?

    Answer: 47 CFR Part 73

    47 CFR Part 73 (specifically Subpart B for FM) governs all technical standards for full-power FM broadcast stations including maximum ERP, HAAT, and antenna requirements.