Uploaded April 2026 | Updated September 2026, 1 week ago
Technician Exam Questions Part 25
T9A – Antennas: vertical and horizontal polarization, concept of antenna gain, definition and types of beam antennas, antenna loading, common portable and mobile antennas, relationships between resonant length and frequency, and dipole pattern.
T9B – Feed lines: types, attenuation vs frequency, selecting. SWR concepts, Antenna tuners (couplers), RF Connector selecting and weather protection.
This episode of Ham College (Episode 138) is dedicated to preparing students for the Amateur Radio Technician Exam, specifically focusing on antenna theory and feed line systems.
Key Topics Covered:
Antennas (T9A): (1:59 - 27:02)
Beam Antennas: Defined as antennas that focus signals in a specific direction (3:08 - 4:27). The Yagi antenna is highlighted as providing the greatest gain (10:53 - 12:30).
Antenna Loading: This process involves electrically lengthening an antenna by using loading coils (4:30 - 5:30).
Polarization: A simple dipole positioned parallel to the Earth's surface is horizontally polarized (6:04 - 7:04).
Dipole Patterns: A half-wave dipole radiates its strongest signal broadside to the antenna (20:17 - 21:56).
Resonant Length: As a dipole's resonant frequency increases, the antenna length must be shortened (9:00 - 9:55). A quarter-wave vertical antenna for 146 MHz is roughly 19 inches long (14:06 - 15:00).
Feed Lines (T9B): (27:02 - 50:00)
Coaxial Cable: The most common feed line in amateur radio because it is easy to use and requires minimal special installation considerations (32:38 - 33:45).
Impedance: 50 ohms is the standard common impedance for coaxial cable in amateur radio (31:20 - 31:40).
SWR (Standing Wave Ratio): Represents how well a load is matched to a transmission line (48:22 - 49:40). Maintaining low SWR is beneficial for reducing signal loss (30:28 - 31:14).
Connectors: Type N connectors are preferred for higher frequencies (38:24 - 38:36), while PL-259 connectors are commonly used at HF and VHF frequencies (40:01 - 40:48).
Technician Exam Questions Part 25
T9A – Antennas: vertical and horizontal polarization, concept of antenna gain, definition and types of beam antennas, antenna loading, common portable and mobile antennas, relationships between resonant length and frequency, and dipole pattern.
T9B – Feed lines: types, attenuation vs frequency, selecting. SWR concepts, Antenna tuners (couplers), RF Connector selecting and weather protection.
This episode of Ham College (Episode 138) is dedicated to preparing students for the Amateur Radio Technician Exam, specifically focusing on antenna theory and feed line systems.
Key Topics Covered:
Antennas (T9A): (1:59 - 27:02)
Beam Antennas: Defined as antennas that focus signals in a specific direction (3:08 - 4:27). The Yagi antenna is highlighted as providing the greatest gain (10:53 - 12:30).
Antenna Loading: This process involves electrically lengthening an antenna by using loading coils (4:30 - 5:30).
Polarization: A simple dipole positioned parallel to the Earth's surface is horizontally polarized (6:04 - 7:04).
Dipole Patterns: A half-wave dipole radiates its strongest signal broadside to the antenna (20:17 - 21:56).
Resonant Length: As a dipole's resonant frequency increases, the antenna length must be shortened (9:00 - 9:55). A quarter-wave vertical antenna for 146 MHz is roughly 19 inches long (14:06 - 15:00).
Feed Lines (T9B): (27:02 - 50:00)
Coaxial Cable: The most common feed line in amateur radio because it is easy to use and requires minimal special installation considerations (32:38 - 33:45).
Impedance: 50 ohms is the standard common impedance for coaxial cable in amateur radio (31:20 - 31:40).
SWR (Standing Wave Ratio): Represents how well a load is matched to a transmission line (48:22 - 49:40). Maintaining low SWR is beneficial for reducing signal loss (30:28 - 31:14).
Connectors: Type N connectors are preferred for higher frequencies (38:24 - 38:36), while PL-259 connectors are commonly used at HF and VHF frequencies (40:01 - 40:48).
