US_TECH_2026_2030

Technician 2026-2030 - Antennas and feed lines

Antennas and feed lines groups the T9 section questions for focused review and easier weak-point tracking.

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Pool: Technician 2026-2030
Questions: 23
Topic: Antennas and feed lines
Region: US

Read the condition in the stem before comparing key terms in the options.

Study rules, calculations, and equipment questions as separate patterns.

After this topic, return to the full pool for mixed practice.

Topic Study Guide

This topic covers the core antenna types, feed line characteristics, and connector selections in amateur radio. Focus on understanding antenna gain, polarization, and the loss characteristics of different coaxial cables.

High-Yield Checks

Antenna Types & Gain: Know that Yagi antennas offer the greatest gain, 5/8-wave antennas have more gain than 1/4-wave, and beam antennas concentrate signals in one direction.
Polarization & Resonance: Antenna polarization is determined by the orientation of the electric field. Shortening a dipole increases its resonant frequency.
Coaxial Cables & Loss: 50 ohms is the standard impedance. Cable loss increases with frequency. RG-213 has less loss than RG-58, and air-insulated hardline has the lowest loss.
Connectors: PL-259 is used for HF and VHF, while Type N is best for frequencies above 400 MHz. All outdoor connectors require weatherproofing.

Trap Patterns

Assuming the PL-259 (historically called a 'UHF' connector) is good for modern UHF. In reality, Type N is required for frequencies above 400 MHz.
Misunderstanding antenna gain. Gain does not magically add power to the transmitter; it focuses existing RF energy in a specific direction.
Confusing physical modifications with electrical 'loading'. Loading means inserting inductors to electrically lengthen the antenna, not adding springs or structural supports.

Review Steps

Group the questions by sub-topic: tackle antenna principles and types first (T9A), then move on to feed lines and connectors (T9B).
Memorize the specific connector types and their frequency limits (compare PL-259 with Type N).
Understand the mathematical relationship between frequency, wavelength, and physical length (e.g., a 2-meter quarter-wave antenna is about 19 inches long).
Review the factors that increase feed line loss and the physical faults (like loose connections) that cause erratic SWR readings.

Quick Checks

Does the electric field or the magnetic field determine the polarization of an antenna?
Which coaxial cable has lower loss at a given frequency: RG-58 or RG-213?
What is the primary function of an antenna tuner?
Which RF connector is most suitable for frequencies above 400 MHz?

Questions in This Topic