Technician T9A: Antenna basics
These are the 11 official questions in group T9A of the 2026–2030 Technician question pool, with the correct answer marked and a plain-English explanation of why it's right. The real exam asks one question from this group.
- T9A01Question 1
What is a beam antenna?
- AAn antenna built from square aluminum beams
- BAn omnidirectional antenna invented by Clarence Beam
- CAn antenna that concentrates signals in one direction Correct
- DAn antenna that focuses the signal into two intense rays
Why: A beam antenna concentrates the signal in one direction.
- T9A02Question 2
Which of the following describes a type of antenna loading?
- AElectrically lengthening by inserting inductors in radiating elements Correct
- BInserting a resistor in the radiating portion of the antenna to make it resonant
- CInstalling a spring in the base of a mobile vertical antenna to make it more flexible
- DStrengthening the radiating elements of a beam antenna to better resist wind damage
Why: Loading coils electrically lengthen a physically short antenna.
- T9A03Question 3
How is the polarization of an antenna described?
- ABy the shape of the driven element
- BBy the orientation of the electric field Correct
- CBy the orientation of the magnetic field
- DBy the direction of radiation
Why: Polarization is described by the orientation of the electric field.
- T9A04Question 4
What is a disadvantage of a handheld radio transceiver’s short flexible antenna compared to a full-sized quarter-wave antenna?
- AIt has low efficiency Correct
- BIt transmits only circularly polarized signals
- CIt is more susceptible to receiver desensitization
- DIt only works on analog signals, not digital ones
Why: A short rubber antenna is convenient, but it radiates much less efficiently than a full quarter-wave.
- T9A05Question 5
Which of the following increases the resonant frequency of a dipole antenna?
- ALengthening it
- BInserting coils in series with radiating wires
- CShortening it Correct
- DAdding capacitive loading to the ends of the radiating wires
Why: A shorter dipole is resonant at a higher frequency.
- T9A06Question 6
Which of the following types of antennas offers the greatest gain?
- A5/8 wave vertical
- BIsotropic
- CJ pole
- DYagi Correct
Why: A Yagi beam has the most gain of the choices.
- T9A07Question 7
What is a potential drawback of using a handheld VHF transceiver inside a vehicle that lacks an externally mounted antenna?
- ASignal strength is reduced due to the shielding effect of the vehicle Correct
- BThe bandwidth of the antenna will decrease, increasing SWR
- CThe SWR might decrease, decreasing the signal strength
- DThe handheld will overheat due to reflected power in the vehicle
Why: The car's metal body shields the signal, reducing strength.
- T9A08Question 8
Why is a 19-inch-long vertical antenna often used on 2 meters?
- AIt has high gain
- BIt is a resonant half-wave
- CIt is a resonant quarter-wave Correct
- DIt has low RF radiation exposure
Why: A quarter-wave at 146 MHz is about 2,808 ÷ 146 ≈ 19 inches.
- T9A09Question 9
What is an advantage of a 5/8-wavelength whip antenna for VHF or UHF mobile service compared to a 1/4-wave antenna?
- AIt has more gain Correct
- BIt radiates at a higher angle
- CIt has lower SWR
- DIt has lower impedance
Why: A 5/8-wave whip has more gain than a 1/4-wave.
- T9A10Question 10
In which direction does a half-wave dipole antenna radiate the strongest signal?
- AEqually in all directions
- BOff the ends of the antenna
- CIn the direction of the feed line
- DBroadside to the antenna Correct
Why: A half-wave dipole radiates strongest broadside, at right angles to the antenna.
- T9A11Question 11
What is antenna gain?
- AThe additional power that is added to the transmitter power
- BThe additional power that is required in the antenna when transmitting on a higher frequency
- CThe increase in signal strength in a specified direction compared to a reference antenna Correct
- DThe increase in impedance on receive or transmit compared to a reference antenna
Why: Gain is the increase in signal in a given direction compared to a reference antenna.