Lesson 2: Radio Wave Propagation
Frequency and wavelength come next, because bands, antennas and modes are all described in those terms.
What you will learn
- T3A Radio wave characteristics: how a radio signal travels, fading, multipath, polarization, wavelength vs absorption; Antenna orientation
- T3B Electromagnetic wave properties: wavelength vs frequency, nature and velocity of electromagnetic waves, relationship of wavelength and frequency; Electromagnetic Spectrum Definitions: UHF, VHF, HF
- T3C Propagation modes: sporadic E, meteor scatter, auroral propagation, tropospheric ducting; F region skip; Line of sight and radio horizon
1. Read
- Radio waves and the spectrum: What a radio wave isHelps with T3B
- Radio waves and the spectrum: Frequency and wavelengthHelps with T3B
- Radio waves and the spectrum: Regions of the spectrumHelps with T3B
- Radio waves and the spectrum: What gets in the wayHelps with T3A
- Radio waves and the spectrum: PolarizationHelps with T3A
- How radio signals travel: Line of sight and the radio horizonHelps with T3C
- How radio signals travel: The ionosphereHelps with T3C
- How radio signals travel: VHF and UHF beyond the horizonHelps with T3C
- All 35 T3 questions with their answers and explanationsEvery group, with the rule or source behind each answer
2. Explore
- Wavelength explorer
Pick 40 m (7.15 MHz), then 20 m (14.2 MHz). Nearly doubling the frequency nearly halves the wavelength, from about 42 meters to about 21 meters.
This is exam question T3B05.
- Propagation conditions
Raise the operating frequency until signals stop returning from the ionosphere and pass into space. UHF signals usually go straight through, which is why UHF simplex rarely reaches past the radio horizon.
This is exam question T3C01.
3. Practice
Practice one group at a time. A group is ready when you have answered every one of its questions and learned at least 80 percent of them; a question counts as learned when your last three answers to it were correct. To review quickly, go through this lesson’s questions as flashcards.
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