## Introduction

A hollow metallic tube of uniform cross-section for transmitting electromagnetic waves by successive reflection from the inner wall of the tube is called a waveguide. A waveguide is a structure that guides waves, such as electromagnetic waves or sound waves with minimal energy loss by restricting energy transmission to one direction

## Waveguide

A waveguide is an electromagnetic feed line used in microwave communications. A waveguide is generally preferred in microwave communications. A waveguide is a special form of transmission line, which is a hollow metal tube. unlike a transmission line, a waveguide has no center conductor.

## Types of Waveguide

There are five types of waveguides.

1. Rectangular Waveguide
2. Circular Waveguide
3. Elliptical Waveguide
4. Single-ridged Waveguide
5. Double-ridged Waveguide

## Characteristics of Waveguide

1. Cut-off Wavelength: The cutoff wavelength for any mode is defined as the maximum wavelength at which the mode will propagate. It is denoted by λc.

2. Group Velocity: Group Velocity can be defined as the rate at which the wave propagates through the waveguide. this can be understood as the rate at which a modulated envelope travels compared to the carrier alone. this modulated wave travels through the waveguide. The equation of group velocity is represented as:

Vg=dw/dk

3. Phase velocity: It is the velocity with which the transmitted wave changes its phase during propagation. It is the velocity of a particular phase of the propagating wave. VP denotes it.

4. Wave Impedance: It is also known as the characteristic impedance. It is defined as the ratio of the transverse electric field to that of the transverse magnetic field during wave propagation at any point inside the waveguide. Zg denotes it.

## Modes in Waveguide

There are two common modes

1. Transverse-magnetic (TM)
2. Transverse-electric (TE)

### 1. Transverse-magnetic (TM)

The magnetic lines of flux are perpendicular to the axis of the waveguide. ”Magnetic flux lines appear as continuous loops”.

### 2. Transverse-electric (TE)

The electric lines of flux are perpendicular to the axis of the waveguide. ”Electric flux lines appear with beginning and end points”.

1. Waveguides are easy to manufacture.
2. They can handle very large power in kilowatts.
3. Power loss is very negligible in waveguides.
4. They offer shallow loss low value of alpha-attenuation through a waveguide, It experiences lower losses than a coaxial cable.
5. It is easy to install the waveguide in a microwave transmission system due to its simple structure on both ends.

1. It is not suitable for operation at power frequencies due to increased dimensions.
2. It is very bulky in size and weight.
3. It is not economical.
4. It supports a narrow band of operation.
5. It is not flexible.

1. #### What are the shapes of waveguides used for transmission?

Rectangular and circular are commonly used. Elliptical, single-ridged, double-ridged are also used.

2. #### Why are waveguides used?

Waveguides are used to transfer both power and communication signals.

3. #### What are the advantages of a waveguide?

Waveguides offer low losses, high power handling capability, and excellent electromagnetic shielding.

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#### Ankita Mishra

Ankita Mishra is a dedicated content writer with a strong technical background, holding a diploma in Electronics and communication. Ankita leverages her technical skills and attention to detail to create informative content.

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