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Waveguides and transmission lines
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Guide EM waves along structures.
Coaxial cables and waveguides carry EM energy with low loss; impedance matching avoids reflections. Characteristic impedance Z₀ = √(L/C) per length.
TV cable 75 Ω.
Mismatches cause standing waves.
In more detail
Transmission lines and waveguides carry electromagnetic energy with controlled impedance and low loss. Coaxial cables and rectangular waveguides are common examples.
Real-world uses
- Coaxial cables carry TV and internet signals.
- Microwave radar uses rectangular waveguides.
- Microwave links and cable television use waveguides and transmission lines to carry signals with little loss.
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Frequently asked questions
What is characteristic impedance?
The ratio of voltage to current for a travelling wave on the line, set by its geometry.
Why match impedances?
Mismatches reflect energy back and reduce power delivered to the load.
What is a waveguide?
A hollow metal tube or structure that guides electromagnetic waves along its length with low loss.
Related topics in AC Circuits & EM Waves
Gamma rays · Polarisation of EM waves · Antennas · Modulation (AM and FM) · Optical fibre communication · Radar