All 35 Ham Radio Technician questions for T3 Radio Waves & Propagation with the correct answers marked and a short explanation for each, from the official 2026-2030 question pool. Test yourself with the free practice exam.
T3A01
Why do VHF signal strengths sometimes vary greatly when the antenna is moved only a few feet?
A. The signal path encounters different concentrations of water vapor
B. VHF ionospheric propagation is very sensitive to path length
C. Multipath propagation cancels or reinforces signals ✓
D. The Doppler effect causes slight frequency shifts which result in changes in signal strength
Why: At VHF, signals reach your antenna by several paths, including direct and reflected from buildings and terrain. Moving a few feet changes how these combine, either reinforcing or canceling each other. This effect is multipath.
T3A02
How does vegetation affect UHF and microwave signals?
A. Causes knife-edge diffraction, distorting voice peaks
B. Absorbs signals, leading to poor reception of weak signals ✓
C. Amplifies signals, improving reception of weak signals
D. Has no effect
Why: Leaves and branches contain water, which absorbs UHF and microwave energy. Trees in the path can significantly weaken signals, making weak signals hard to receive.
T3A03
What antenna polarization is normally used for long-distance CW and SSB contacts on the VHF and UHF bands?
A. Right-hand circular
B. Left-hand circular
C. Horizontal ✓
D. Vertical
Why: Long-distance (weak-signal) CW and SSB work on VHF/UHF traditionally uses horizontal polarization. FM and repeaters mostly use vertical polarization, so the two groups' antennas differ.
T3A04
What is the effect of antenna cross-polarization over a line-of-sight VHF or UHF path?
A. Modulation sidebands might become inverted
B. Received signal strength is reduced ✓
C. Signals have an echo effect
D. Nothing significant will happen
Why: On line-of-sight paths, polarization is maintained, so a horizontal antenna receiving a vertically polarized signal (cross-polarization) sees a large loss, often 20 dB or more, and signals are much weaker.
T3A05
When using a directional antenna, how might your station be able to communicate with a distant repeater if buildings or obstructions are blocking the direct line of sight path?
A. Change from vertical to horizontal polarization
B. Try to find a path that reflects signals to the repeater ✓
C. Try the long path
D. Increase the antenna SWR
Why: If a building blocks the direct path, aim your directional antenna at a hill or large structure that can reflect your signal toward the repeater. Polarization changes or higher SWR will not help.
T3A06
What is the meaning of the term “picket fencing”?
A. Alternating transmissions during a net operation
B. Rapid flutter on mobile signals due to multipath propagation ✓
C. A type of ground system used with vertical antennas
D. Interference from cable TV in the form of carriers at fixed intervals across the band
Why: Picket fencing is the rapid flutter heard on mobile VHF/UHF FM signals as a moving vehicle passes through areas where multipath signals reinforce and cancel, like passing a picket fence.
T3A07
What weather condition might decrease range at microwave frequencies?
A. High winds
B. Low barometric pressure
C. Precipitation ✓
D. Colder temperatures
Why: At microwave frequencies, rain, snow and other precipitation absorb and scatter radio energy, reducing range. Wind and pressure have little direct effect.
T3A08
What is a likely cause of irregular fading of signals propagated by the ionosphere?
A. Frequency shift due to Faraday rotation
B. Interference from thunderstorms
C. Intermodulation distortion
D. Random combining of signals arriving via different paths ✓
Why: Signals arriving through the ionosphere follow several paths that change constantly. Their random combining, sometimes in phase and sometimes out of phase, causes irregular fading.
T3A09
Which of the following results from the fact that signals propagated by the ionosphere are elliptically polarized?
A. Digital modes are unusable
B. Either vertically or horizontally polarized antennas may be used for transmission or reception ✓
C. FM voice is unusable
D. Both the transmitting and receiving antennas must be of the same polarization
Why: The ionosphere changes a signal's polarization so it arrives elliptically polarized, with both vertical and horizontal components. So either a vertical or a horizontal antenna works for skywave signals.
T3A10
What effect does multi-path propagation have on data transmissions?
A. Transmission rates must be increased by a factor equal to the number of separate paths observed
B. Transmission rates must be decreased by a factor equal to the number of separate paths observed
C. No significant changes will occur if the signals are transmitted using FM
D. Error rates are likely to increase ✓
Why: Multipath causes delayed copies of a data signal to overlap and distort the received symbols. This raises error rates, often requiring retransmissions or slower data rates.
T3A11
Which region of the atmosphere can reflect HF radio waves?
A. The stratosphere
B. The troposphere
C. The ionosphere ✓
D. The electrosphere
Why: The ionosphere is a region of the upper atmosphere ionized by solar radiation. It refracts HF waves back to Earth, allowing long-distance skip communications. The troposphere and stratosphere do not reflect HF.
T3A12
What effect does fog or rain have on 10-meter and 6-meter band signals?
A. Absorption
B. Little effect ✓
C. Deflection
D. Increased range
Why: Fog and rain have little effect at 10 and 6 meters because the wavelengths (about 10 and 6 meters) are much larger than raindrops. Rain absorption matters mainly at microwave frequencies.
T3B01
What is the relationship between the electric and magnetic fields of an electromagnetic wave?
A. They travel at different speeds
B. They are in parallel
C. They revolve in opposite directions
D. They are at right angles ✓
Why: In an electromagnetic wave, the electric and magnetic fields are perpendicular (at right angles) to each other and to the direction of travel. Both travel at the same speed.
T3B02
What property of a radio wave defines its polarization?
A. The orientation of the electric field ✓
B. The orientation of the magnetic field
C. The ratio of the energy in the magnetic field to the energy in the electric field
D. The ratio of the velocity to the wavelength
Why: A radio wave's polarization is defined by the orientation of its electric field. A vertical antenna produces a vertical electric field, so its signal is vertically polarized.
T3B03
What are the two components of a radio wave?
A. Impedance and reactance
B. Voltage and current
C. Electric and magnetic fields ✓
D. Ionizing and non-ionizing radiation
Why: A radio wave is an electromagnetic wave made of an electric field and a magnetic field, which regenerate each other as the wave travels. Voltage and current describe circuits, not the wave.
T3B04
What is the velocity of a radio wave traveling through free space?
A. Speed of light ✓
B. Speed of sound
C. 0.86 times the speed of light
D. 1.86 times the speed of sound
Why: Radio waves are electromagnetic waves, like light, so in free space they travel at the speed of light, about 300,000,000 meters per second. In feed lines they travel slower.
T3B05
What is the relationship between wavelength and frequency?
A. Wavelength gets longer as frequency increases
B. Wavelength gets shorter as frequency increases ✓
C. Wavelength is constant at all frequencies
D. Wavelength and frequency increase as path length increases
Why: Wavelength and frequency are inversely related: wavelength equals velocity divided by frequency. As frequency increases, wavelength gets shorter. For example, 300 / 30 MHz is 10 meters, while 300 / 300 MHz is 1 meter.
T3B06
What is the formula for converting frequency to approximate wavelength in meters?
A. Wavelength in meters equals frequency in hertz multiplied by 300
B. Wavelength in meters equals frequency in hertz divided by 300
C. Wavelength in meters equals frequency in megahertz divided by 300
D. Wavelength in meters equals 300 divided by frequency in megahertz ✓
Why: Wavelength in meters is approximately 300 divided by frequency in MHz, because radio waves travel about 300 million meters per second. Example: 300 / 146 MHz is about 2.05 meters, hence the '2-meter' band.
T3B07
In addition to frequency, which of the following is used to identify amateur radio bands?
A. The approximate wavelength in meters ✓
B. Traditional letter/number designators
C. Channel numbers
D. All these choices are correct
Why: Amateur bands are commonly named by their approximate wavelength in meters, such as 2 meters for 144 to 148 MHz or 70 centimeters for 420 to 450 MHz. Channel numbers are not used.
T3B08
What frequency range is referred to as VHF?
A. 30 kHz to 300 kHz
B. 30 MHz to 300 MHz ✓
C. 300 kHz to 3000 kHz
D. 300 MHz to 3000 MHz
Why: VHF (very high frequency) covers 30 to 300 MHz, which includes the 6-meter, 2-meter and 1.25-meter amateur bands. 300 to 3000 MHz is UHF, and 3 to 30 MHz is HF.
T3B09
What frequency range is referred to as UHF?
A. 30 to 300 kHz
B. 30 to 300 MHz
C. 300 to 3000 kHz
D. 300 to 3000 MHz ✓
Why: UHF (ultra high frequency) covers 300 to 3000 MHz, which includes the 70-centimeter, 33-centimeter and 23-centimeter amateur bands. The range just below it, 30 to 300 MHz, is VHF.
T3B10
What frequency range is referred to as HF?
A. 300 to 3000 MHz
B. 30 to 300 MHz
C. 3 to 30 MHz ✓
D. 300 to 3000 kHz
Why: HF (high frequency) covers 3 to 30 MHz, which includes the 80-meter through 10-meter amateur bands. 300 to 3000 kHz is MF, and 30 to 300 MHz is VHF.
T3B11
What is the approximate velocity of a radio wave in free space?
A. 150,000,000 meters per second
B. 300,000,000 meters per second ✓
C. 300,000,000 miles per hour
D. 150,000,000 miles per hour
Why: Radio waves in free space travel at the speed of light, about 300,000,000 meters per second (3 x 10^8 m/s). This is the number behind the 300 / MHz wavelength formula.
T3B12
Which of these frequencies travels at the highest velocity in free space?
A. Microwaves
B. UHF
C. VHF
D. All radio frequencies travel at the same velocity ✓
Why: All electromagnetic waves travel at the speed of light in free space, regardless of frequency. Only the wavelength changes with frequency.
T3C01
Why are simplex UHF signals rarely heard beyond their radio horizon?
A. They are too weak to go very far
B. FCC regulations prohibit them from going more than 50 miles
C. UHF signals are usually not propagated by the ionosphere ✓
D. UHF signals are absorbed by the ionospheric D region
Why: UHF signals normally pass through the ionosphere instead of being refracted back to Earth, so they travel mostly line of sight. Signals rarely go beyond the radio horizon. No FCC distance limit exists.
T3C02
What is a characteristic of HF communication compared with communications on VHF and higher frequencies?
A. HF antennas are generally smaller
B. HF accommodates wider bandwidth signals
C. Long-distance ionospheric propagation is far more common on HF ✓
D. There is less atmospheric interference (static) on HF
Why: The ionosphere regularly refracts HF signals back to Earth, so long-distance skip propagation is far more common on HF than on VHF and above. HF antennas are larger and there is more static, not less.
T3C03
What is one characteristic of VHF signals received via auroral backscatter?
A. They are often received from 10,000 miles or more
B. They are distorted, with a characteristic raspy sound ✓
C. They occur only during winter nighttime hours
D. They are generally strongest when your antenna is aimed west
Why: Signals reflected off the moving, irregular aurora are distorted and sound raspy or buzzy, so CW is often favored. Auroral contacts are typically made by pointing the antenna north, not west.
T3C04
Which of the following types of propagation is most commonly associated with occasional strong signals on the 10-, 6-, and 2-meter bands from beyond the radio horizon?
A. Backscatter
B. Sporadic E ✓
C. D region absorption
D. Gray-line propagation
Why: Sporadic E is caused by patches of dense ionization in the ionosphere's E region. It can bring sudden, strong signals from hundreds to over a thousand miles away on 10, 6 and occasionally 2 meters.
T3C05
Which of the following effects may allow radio signals to travel beyond obstructions between the transmitting and receiving stations?
A. Knife-edge diffraction ✓
B. Faraday rotation
C. Quantum tunneling
D. Doppler shift
Why: Knife-edge diffraction occurs when radio waves bend around a sharp edge, such as a ridge or building, letting signals reach behind obstructions that would otherwise block line of sight.
T3C06
What type of propagation is responsible for allowing over-the-horizon VHF and UHF communications to ranges of approximately 300 miles on a regular basis?
A. Tropospheric ducting ✓
B. D region refraction
C. F2 region refraction
D. Faraday rotation
Why: Tropospheric ducting traps VHF and UHF signals in a layer of the lower atmosphere, letting them travel well beyond the horizon, often around 300 miles. D and F region effects involve the ionosphere instead.
T3C07
What band is best suited for communicating via meteor scatter?
A. 33 centimeters
B. 6 meters ✓
C. 2 meters
D. 70 centimeters
Why: 6 meters is best for meteor scatter because ionized meteor trails reflect lower VHF frequencies most effectively. Higher bands like 70 and 33 centimeters reflect much less.
T3C08
What causes tropospheric ducting?
A. Discharges of lightning during electrical storms
B. Sunspots and solar flares
C. Updrafts from hurricanes and tornadoes
D. Temperature inversions in the atmosphere ✓
Why: Tropospheric ducting occurs when a temperature inversion, a layer of warm air above cooler air, forms a duct that guides VHF and UHF signals far beyond the normal radio horizon.
T3C09
What is generally the best time for long-distance 10-meter band propagation via the F region?
A. From dawn to shortly after sunset during periods of high sunspot activity ✓
B. From shortly after sunset to dawn during periods of high sunspot activity
C. From dawn to shortly after sunset during periods of low sunspot activity
D. From shortly after sunset to dawn during periods of low sunspot activity
Why: The F region is most strongly ionized by sunlight during daytime, and high sunspot activity increases ionization enough to refract 10-meter signals. So the best time is dawn to shortly after sunset, near sunspot peaks.
T3C10
Which of the following bands may provide long-distance communications via the ionosphere’s F region during the peak of the sunspot cycle?
A. 6 and 10 meters ✓
B. 23 centimeters
C. 70 centimeters and 1.25 meters
D. All these choices are correct
Why: During the peak of the sunspot cycle, F region ionization becomes strong enough to refract 10-meter and sometimes 6-meter signals, allowing worldwide contacts. UHF bands pass through the ionosphere.
T3C11
Why is the radio horizon for VHF and UHF signals more distant than the visual horizon?
A. Radio signals move somewhat faster than the speed of light
B. Radio waves are not blocked by dust particles
C. The atmosphere refracts radio waves slightly ✓
D. Radio waves are blocked by dust particles
Why: The atmosphere's density decreases with height, which bends (refracts) radio waves slightly back toward Earth. This makes the radio horizon roughly 15 percent farther than the visual horizon.