The waveguide is a particular type of transmission line that is a hollow tube made of metal. The tube’s wall is used to distribute inductance. The spaces between them offer the capacitance that is distributed.
Waveguides can be used only for extremely high frequencies signals, where the wavelength is close to the cross-sectional dimension of the guide. In the lower frequency range, waveguides are not suitable as transmission lines for electrical signals.
A waveguide could have rectangular, circular, or elliptical cross-sections. The rectangular waveguide is the most frequently used for connections with a relatively short length. In comparison to coaxial lines, waveguides offer significant advantages. However, in reality, these advantages are only available with frequencies greater than 1 GHz. They provide a variety of benefits over coaxial or two-wire transmission lines. The most significant advantage is that waveguides allow the propagation of energy with less loss. The magnetic and electric fields utilized to transport energy are at zero on the metal surface. This means that these fields are restricted to the area within the waveguide’s walls. The electromagnetic fields inside the waveguide are shielded completely, from inside towards the exterior (radiation reductions are minimal) and from outside into the waveguide, giving excellent protection against very weak unwanted signals.
Coaxial Cables Disadvantages
Coaxial cables in the frequency range of more than 1000 MHz suffer from numerous disadvantages for high power transmissions, like high attenuation and low flashover resistance. Their line capacitances and inductances cause the losses in attenuation, and they suffer from the skin effect and increase with increasing frequency of transmission. Therefore, coaxial cables above 36 GHz aren’t recommended because of their large attenuation. In addition, the variable arc or flashover resistance in coaxial cables is reduced by the small distance between the outer and inner conductors. This is a good thing for low power signals, but when used in high-performance ranges, they can cause unacceptably high losses.
Usage of Waveguides as a Transmission Line
When used as transmission lines, they’re much simpler than two-conductor cables, especially coaxial cables, in design and maintenance.
With only a single conductor, there are no concerns with proper conductor-to-conductor spacing
or the dielectric material’s consistency since the only dielectric in a waveguide is air. Moisture isn’t a severe issue with waveguides like it is in coaxial cables, which is why waveguides are typically not required to undergo gas “filling.”
Waveguides can be thought of as conduits for electromagnetic energy, with the waveguide acting more than a “director” of energy rather than signal conductors in the conventional sense.
In a way, the transmission lines all function as conduits for energy, transferring waves or pulses of high frequency and directing them in the same way that the banks of rivers direct the tidal waves.
Since waveguides are single-conductor structures that transmit electricity through the waveguide, they are completely different from the electrical energy transmitted along two-conductor transmission lines.
Is a coaxial cable a waveguide?
A waveguide is any one of the devices in the class that restricts and directs the propagation of electromagnetic waves, including radio waves, infrared radiation, or visible light. They come in many shapes and shapes. Examples are hollow metal tubes, coaxial cables, and optical fibers.
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