In this article, we will discuss the basics of waveguides and show 15 different types of waveguide symbols.
Introduction of Waveguide
Any surface separating two media of distinctly different conductivities or permittivities has a guiding effect on electromagnetic waves. For example, a rod of dielectric material, such as polystyrene, can carry a high-frequency wave, somewhat as a glass fiber conducts a beam of light. The best guiding surface, however, is between a good dielectric and a good conductor.
In a broad sense, all kinds of transmission lines, including coaxial cables and parallel wires, are waveguides. In practice, however, the term waveguide has come to signify a hollow metal tube or pipe used to conduct electromagnetic waves through its interior. They were first extensively used in radar sets during World War II, operating at wavelengths of between 10 and 3 cm.
A waveguide can be almost any shape. The most popular shape is rectangular, but some use of circular and even more exotic shapes is made. We shall mainly study the rectangular waveguide operating in the TE10 mode. We shall learn more about this terminology shortly.
Like coaxial lines, waveguides are perfectly shielded hence, no radiation loss. The attenuation of a hollow pipe is less, and the power capacity is greater than that of a coaxial line of the same size at the same frequency. Most of the copper loss of a coaxial line occurs in the thin inner conductor; hence, its elimination in a waveguide reduces attenuation and increases the power capacity. It also simplifies the construction and makes the line more rugged.
Waveguide Symbol
Figure 1:
Circular Waveguide Symbol
Overhead line
Figure 2: Coaxial waveguide
Figure 3:
coupling by the probe to space (on VHF, UHF, SHF circuits)
Open circuit on coax
Open circuit on waveguide
Figure 4: Dielectric filled metallic rectangular waveguide symbol
Figure 5: Gas-filled rectangular waveguide
Figure 6:
Movable short circuit on coax
Movable short circuit on waveguide circuit
Figure 7: Optical fiber symbol
Figure 8: optical shielding symbol
Figure 9: Rectangular waveguide symbol
Figure 10:
Short circuit on coax
short circuit on waveguide circuit
Figure 11: Solid dielectric rectangular waveguide