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Wave Guide Components

BASIC PRODUCT DETAILS

RF Waveguide components: - About, Operation, Application, Design:

An RF Waveguide is an elemental structure that guides RF and Microwave waves, ( electromagnetic waves or sound ) in one direction with minimal energy loss. Wave Guide components include Circulator, waveguide directional couplers, waveguide load, tuners, waveguide Tee, straight waveguide sections and bends etc.

  • RF and microwave waveguide components are used to transmit, the microwave energy generated from the source like magnetron to the load like an antenna.

To learn about RF and Microwave communication systems and RF components, we recommend checking the following RF and Microwave articles about bestsellers.

To understand the RF waveguides in a better way, we recommend understanding the following systems.

In this RF and Microwave waveguide article, we will cover,

  • What are waveguide components?
  • Types of RF waveguide components?
  • Advantages and Applications of waveguides?
  • Specifications that need to consider for RF waveguides.
  • RF and microwave optical components Manufacture.

Design and Application

Different types of waveguides:

Waveguides are classified on the base of the signal which propagates through them, basically, we can classify it as RF and Microwave waveguide, Optical waveguide and Acoustic waveguide.

Radio-frequency waveguides:

Radiofrequency waveguides are used for transferring RF and Microwave communication signals. These waveguides are designed to carry electromagnetic RF and microwave frequency waves. These waveguides can be constructed from either dielectric or conductive materials on the base of frequency.

Optical waveguides:

Optical fibre is a type of optical Waveguide which is used to transfer the optical signals by total internal reflection. These waveguides are manufactured by using dielectric material with high permittivity, surrounded by a material with lower permittivity.

Acoustic waveguides:

An acoustic waveguide is used to guide the sound waves as electromagnetic waves on a transmission line. Waves on a telephone line string is an example of an acoustic waveguide.

Types of RF and Microwave Waveguide components:

There are many types of RF and Microwave waveguide components are available for the transmission of high power and high-frequency RF waves. Most of the waveguide components are used as a part of the measurement test bench. A few of the commonly used waveguide components are listed below.

Waveguide sections ( Straight, bend, flexible etc):

RF Waveguide sections are of different types like hard type, flexible, straight, bends, twists etc. These are transitions piece that is used to efficiently transmit RF and microwave energy from the source side to the load. RF and Microwave Waveguide can vary in size and shape and also many manufacturers offer customized solutions as per the application requirements.

  • The most common shapes are rectangular or circular waveguides, and size is dependent on the operating frequency and propagation mode of the signal need to transmit.

Waveguide Circulator:

Waveguide Circulators are three-port or four-port waveguide components that selectively direct the energy from one port to the next nearby port. Ferrite technology is utilized to direct energy to a specific waveguide port based upon the wave propagation direction.

  • Waveguide Circulators are primarily used as an Isolator by terminating one port and as a duplexer for directing the transmitter signal to the waveguide antenna and received signal to the received patch.

Waveguide Isolator:

Waveguide Isolators are three-port waveguide structures that offer isolation for the reflection signal from the load to the source. It is similar to the Circulator with a waveguide terminator at one port. The reflected energy from the attached load will be circulated to the nearby port which is terminated with a waveguide terminator. Waveguide isolators are mainly used with Magnetron to protect it from the reflected energy from the load.

Waveguide Load / Terminator:

A waveguide load or waveguide terminator is used to terminate the wave propagated over the waveguide section by absorbing microwave energy received from the microwave system. Waveguide terminators are often used in Circulators for terminating load to make it an Isolator or as a test load for RF generators. The selection of the waveguide load is based on its power handing rate.

RF Waveguide Attenuators:

Waveguide attenuators are used to attenuate the signal strength when it passes through it. There are fixed and variable attenuators are available with various power handling capabilities and various attenuation values ranging up to 40 dB.

Low Noise Waveguide Front Ends:

Low Noise waveguide front ends are used to reduce frequency pulling for achieving the desired noise levels and get high performance received signal. GaAs FET and HEMT technology are used in the waveguide sections to improve the performance of the noise rejection by the amplification of the desired signal and decreasing the noise factor.

RF Waveguide Switches:

RF waveguide switches are switching assemble made of waveguides. The switching is controlled by an external electrical interface with the control circuit associated with it. In general, mechanical and electrical waveguide switches are available. It is used to direct the electromagnetic signal among different channels. 

Waveguide RF Filters:

Waveguide RF filters are used to filter out a particular signal while passing through the waveguide sections. Waveguide filters are of low pass, High pass, bandpass and band-reject types.

RF Waveguide Tees: 

Waveguide RF tees are components that have two or more branches that allow input RF signal to branch out into two or more output lines. Waveguide tees work like a waveguide coupler by allowing one signal to pass through the section and the other for monitoring purposes.

Waveguide RF Coupler:

Waveguide couplers are used to couple a portion of the propagated electromagnetic wave through it. The level of the coupled signal is based on the coupling factor of the coupler. There are fixed and variable couplers are available in the market. The coupling factor of the waveguide couplers is in the range of 10, 20, 30 dB etc.

RF Waveguide TR Limiters:

Waveguide TR limiters consist of bandpass filters to protect against spurious emanations and externally biased diodes to protect the load from microwave high power signals from the source. Limiters are basically used to limit the signal propagation over the waveguides.

Waveguide Tuner:

Waveguide RF Tuners is a type of waveguide that is used to match the source impedance to the load impedance. Waveguide tuners offer the most efficient coupling and it will help to minimize the generation of the reflected power at the load to the source interface. Waveguide tuners are available as manual as well as electrical tuners.

  • Electrical tuners have motorized tuning stubs to tune to required load impedance with the help of a microprocessor.

Working Principle of RF Waveguide:

A waveguide is a hollow metallic conductor with the dimension of one-half wavelength with a circular or rectangular cross-section. Conductive or dielectric materials are used for the construction of the waveguides depending on the frequency they need to transmit. The size of the waveguide is inversely proportional to the frequency. i.e. for lower frequency transmission ( larger wavelength), a larger waveguide size is required. 

  • Example: A Microwave waveguide designed for transmitting extremely high frequency(EHF) will have a width of millimetres.

For high power transmission Waveguides, to inhibit arcing and prevent multiplication, they will be filled with pressurized gas. The dimensions of the waveguide determine which frequency (wavelengths) it can support, and in which modes. The radio frequencies below the wave guide's cutoff frequency will not propagate through the waveguide.

Propagation of electromagnetic waves in Waveguide:

Due to the total internal reflection of the electromagnetic wave at the walls of waveguides, the waves are confined to the interior of it and propagate in one direction. Waveguides will have a coupling flange ( based on frequency) on both ends for connecting to other waveguides or to any other source of electromagnetic wave by screwing it together to form the complex shapes to meet the applications.

  • Electromagnetic waves will propagate through the waveguides on its E-plane, H-plane and the transverse plane of the rectangular waveguide cross-section.

Advantages and Disadvantages of RF Waveguide communication systems:

RF waveguide components are used mainly for high power and high-frequency microwave signal transmission (mm-wave application). Following are the advantages and disadvantages of Waveguide Components for RF and Microwave applications:

Advantages of waveguide components:

  • Waveguides are durable and strong in structure.
  • Waveguides will have very little chance of leakage of energy.
  • Waveguides handle high power and wide bandwidth energy transmission.
  • Waveguides behave like a high pass filter and least amount of power loss in a high-frequency application.

Disadvantages:

  • The installation cost is higher.
  • The lower frequency size of the waveguides will be bulky.
  • Flexibility in waveguide rooting is lesser than a co-axial cable.

Application of RF Waveguide Components:

  • Waveguides are used as a simple transmission line.
  • Waveguides are used to make passive components like Coupler, filters, horn antennas, etc for high power applications.
  • Waveguide couplers are used to tap and measure high power signals regularly.
  • For high frequencies applications, the waveguide is a better choice than a co-axial cable.
  • Waveguide components are used on high power test benches.

Basics & Selection Feature

Main specifications need to consider in the selection of RF waveguide components: 

When selecting a waveguide component for the communication system design, or for the transmission of very high power and frequency signal following are the few parameters that need to consider for the ideal applications.

The frequency range / Flange type of waveguides: 

The frequency of the waveguide depends on the internal dimension of the waveguide and the flange type it is used. For each frequency band, there is a specific type of flange and connectors available. The designer needs to select a suitable flange type as per the required frequency of operation. In general, waveguides are available with flanges from WR-22 to WR-650

Insertion loss of waveguides:

Insertion loss of the waveguide indicates the loss in RF power level when the signal is fed into the waveguides. In General, the propagation loss of the waveguides is very less in comparison to the co-axial components.

Power handling:

Power handling indicates the amount of RF power it can handle without affecting any of the other electrical characteristics. In general, waveguides are designed to handle very high power in the range of Kilo / MegaWatt ranges even at higher frequencies.

Size and the material used:

For the signal transmission applications inside a system, the size of the waveguides are important as it consumes more space than a co-axial system. The size of the waveguides will decrease with respect to the increase in frequency. Waveguides can be manufactured using many materials like Strong and light aluminium, copper, browns, gold coating material etc. Life and the performance of the waveguide depend on the base of the material used.

Environmental Parameters:

As most of the waveguides are used in the external environments environmental parameters like temperature, pressure handling, humidity etc need to check and match to the requirements.

Conclusion:

Now for most of the high power and high-frequency applications, waveguides are the prime choice than a co-axial component due to waveguides stability, low loss and cost of implementation.

  • Check out the waveguide manufacturers section for the list of waveguide components manufacturers listed on the RFMWC website and select suitable manufacturers from your country for the design requirements.

If you would like to add any specific RF or millimetre waveguide component manufacture details to this article, please feel free to contact us over the manufactures registration page.

Thanks & Regards

RFMWC



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