Waveguide Tutorial Includes:
Waveguide basics Waveguide modes Waveguide impedance & matching Waveguide cut-off-frequency Waveguide flanges Waveguide junctions Waveguide bends Flexible waveguide Waveguide types & sizes
Waveguides come in a variety of sizes so that they can meet the variety of different requirements for use in many different frequency bands.
In order to bring order to the market, different waveguide standards have been introduced. The most common series are the WG and WG waveguide standards.
Waveguide sizes and waveguide dimensions determine the properties of the waveguide, including parameters such as the waveguide cut off frequency and many other properties.
Waveguide sizes and waveguide dimensions have been standardised to enable waveguides from different manufacturers to be used together. In this way the industry is able to benefit from the ability to use waveguide with known properties, etc.
Waveguide types: standards
There are a number of different standards for differnet types of waveguide. These tend to be country specific. Some of the major standards include:
- WR waveguide system: EIA designation (Standard US) using a WR designator to indicate the size. The designator for a size consists of the letters WR followed by numerals indicating the lowest frequency for which they were designed for use. The letters WR stand for Waveguide Rectangular.
- WG waveguide system: RCSC Designation (Standard UK). The waveguides types are given designators which comprise the letters WG followed by one or two numerals, e.g. WG10.
Both systems are in widespread use and enable the waveguide sizes to be matched and known.
WR waveguide sizes & designations
The WR waveguide designation system is used within the USA and is also widely used in many other areas around the globe. It is popualr because many WR series waveguide parts are made within the USA and these are widely exported. Like the WG waveguide sizes, the WR waveguide designations start with the letters WR.
|WR waveguide dimensions, sizes and waveguide cut-off frequencies
for rigid rectangular RF waveguides
|WR Designation||WG Equivalent||Standard Freq Range GHz||Inside dimensions (inches)|
|WR340||WG9A||2.20 - 3.30||3.400 x 1.700|
|WR284||WG10||2.60 - 3.95||2.840 x 1.340|
|WR229||WG11A||3.30 - 4.90||2.290 x 1.150|
|WR187||WG12||3.95 - 5.85||1.872 x 0.872|
|WR159||WG13||4.90 - 7.05||1.590 x 0.795|
|WR137||WG14||5.85 - 8.20||1.372 x 0.622|
|WR112||WG15||7.05 - 10.00||1.122 x 0.497|
|WR90||WG16||8.2 - 12.4||0.900 x 0.400|
|WR75||WG17||10.0 - 15.0||0.750 x 0.375|
|WR62||WG18||12.4 - 18.0||0.622 x 0.311|
|WR51||WG19||15.0 - 22.0||0.510 x 0.255|
|WR42||WG20||18.0 - 26.5||0.420 x 0.170|
|WR28||WG22||26.5 - 40.0||0.280 x 0.140|
|WR22||WG23||33 - 50||0.224 x 0.112|
|WR19||WG24||40 - 60||0.188 x 0.094|
|WR15||WG25||50 - 75||0.148 x 0.074|
|WR12||WG26||60 - 90||0.122 x 0.061|
It can be seen from the table that the WR number is taken from the internal measurement in mils of the wider side of the waveguide.
WG waveguide sizes and dimensions
The details including cut-off frequency as well as the waveguide dimesions and sizes are given below are for some of the more commonly used rigid rectangular waveguides.
|WG waveguide dimensions, sizes and waveguide cut-off frequencies
for rigid rectangular RF waveguides
|WG Design||Freq range*||Waveguide cut off*||Theoretical attn
|Material||Band||Waveguide dimensions (mm)|
|WG00||0.32 - 0.49||0.256||0.051 - 0.031||Alum||B||584 x 292|
|WG0||0.35 - 0.53||0.281||0.054 - 0.034||Alum||B,C||533 x 267|
|WG1||0.41 - 0.625||0.328||0.056 - 0.038||Alum||B,C||457 x 229|
|WG2||0.49 - 0.75||0.393||0.069 - 0.050||Alum||C||381 x 191|
|WG3||0.64 - 0.96||0.513||0.128 - 0.075||Alum||C||292 x 146|
|WG4||0.75 - 1.12||0.605||0.137 - 0.095||Alum||C,D||248 x 124|
|WG5||0.96 - 1.45||0.766||0.201 - 0.136||Alum||D||196 x 98|
|WG6||1.12 - 1.70||0.908||0.317 - 0.212||Brass||D||165 x 83|
|WG6||1.12 - 1.70||0.908||0.269 - 0.178||Alum||D||165 x 83|
|WG7||1.45 - 2.20||1.157||D,E||131 x 65|
|WG8||1.70 - 2.60||1.372||0.588 - 0.385||Brass||E||109 x 55|
|WG8||1.70 - 2.60||1.372||0.501 - 0.330||Alum||E||109 x 55|
|WG9A||2.20 - 3.30||1.736||0.877 - 0.572||Brass||E,F||86 x 43|
|WG9A||2.20 - 3.30||1.736||0.751 - 0.492||Alum||E,F||86 x 43|
|WG10||2.60 - 3.95||2.078||1.102 - 0.752||Brass||E,F||72 x 34|
|WG10||2.60 - 3.95||2.078||0.940 - 0.641||Alum||E,F||72 x 34|
|WG11A||3.30 - 4.90||2.577||F,G||59 x 29|
|WG12||3.95 x 5.85||3.152||2.08 - 1.44||Brass||F,G||48 x 22|
|WG12||3.95 x 5.85||3.152||1.77 - 1.12||Alum||F,G||48 x 22|
|WG13||4.90 - 7.05||3.711||G,H||40 x 20|
|WG14||5.85 - 8.20||4.301||2.87 - 2.30||Brass||H||35 x 16|
|WG14||5.85 - 8.20||4.301||2.45 - 1.94||Alum||H||35 x 16|
|WG15||7.05 - 10.0||5.26||4.12 - 3.21||Brass||I||29 x 13|
|WG15||7.05 - 10.0||5.26||3.50 - 2.74||Alum||I||29 x 13|
* waveguide cut off frequency in GHz and for TE10 mode
Alum = Aluminium
Waveguide type choice
It is important to choose the right type of waveguide. Each type has different dimensions and this will give it different properties, the cut-off frequency being particularly important, along with the overall recommended frequency range.
The material used in the waveguide will also help dictate some properties. Low resistance materials help to keep losses to a minimum, whereas light weight materials like aluminium keep the weight to a minimum.
Balancing all the different requirements makes sure that the best choice is made for any given application.
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