Antennas & Feedlines Flashcards
7 cards from real Ham Radio Technician Test practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Antennas & Feedlines flashcards as text
What is the effect of operating an antenna significantly off its resonant frequency without a tuner?
Answer: High SWR and increased feedline loss
Operating an antenna off-resonance causes a high SWR, which increases feedline losses and can stress the transmitter's output stage.
For a vertical antenna mounted on a vehicle rooftop, the car body serves as:
Answer: The ground plane
The metal vehicle body acts as the ground plane, providing the RF return path for the vertical antenna.
What does antenna 'gain' mean in practical terms?
Answer: Concentrating radiated power in a preferred direction compared to a reference antenna
Antenna gain is a measure of directivity — it focuses power in certain directions at the expense of others, not creating new power.
Which connector type is commonly used with RG-8 or RG-213 coax for HF amateur radio?
Answer: PL-259 (UHF connector)
The PL-259 (sometimes called a UHF connector despite its name) is standard for HF amateur radio applications with large-diameter coax.
What is a J-pole antenna?
Answer: A half-wave radiator fed at the base via a quarter-wave matching stub
The J-pole uses a quarter-wave matching section (the 'J' foot) to feed a half-wave vertical element at its natural current maximum.
What is 'coax velocity factor' and why does it matter?
Answer: The speed of the signal in coax relative to free space; affects electrical length calculations
Velocity factor (typically 0.66–0.85 for common coax) means signals travel slower in coax than in air, shortening the electrical wavelength.
What is the approximate free-space wavelength at 146 MHz?
Answer: About 2 meters (6.6 feet)
At 146 MHz, the free-space wavelength is approximately 2 meters — which is why this band is called the '2-meter band.'