Checkpoint: T3C — HAM Trainer

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

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

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

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

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

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

T3C07 What band is best suited for communicating via meteor scatter?

A 33 centimeters B 6 meters C 2 meters D 70 centimeters

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

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

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

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