Ridge Waveguide basics

As we know bandwidth of the rectangular waveguide is very less. TE¹⁰ mode is dominant mode in the rectangular waveguide and it has cutoff wavelength of about 2a. Hence dimension of waveguide along X diraction should be equal to or less than 2a for dominant mode of propagation.

For a/b ratio equals two, next higher order mode will be TE²⁰ or TE⁰¹ which will have cutoff wavelength equals either 2b or a. (As a=2b, i.e. broad dimension= 2 (narrow dimension). But dimensions of the waveguide is chosen such that only dominant mode can propagate.

The ridge waveguide is made using rectangular waveguide by adding conducting ridges along the center of the top and bottom walls. An inward perturbation of the waveguide walls at a position of high E will lower the cutoff frequency. At the position of high H will raise the cutoff frequency. These ridges will lower the cutoff frequency of the dominant mode and will raise the cutoff frequency of the next higher order modes. Hence higher range of single mode of operation can be obtained using this technique. This results into higher bandwidth of operation.

Following are the advantages and disadvantages of the ridge waveguide compare to the conventional waveguide of the same dimension.

Advantages of Ridge Waveguide

•  It is used for impedance matching purpose. This is because it help decrease the characteristic impedance of the guide.
•  It increases the bandwidth of operation.

Disadvantages of Ridge Waveguide

•  It will have less power handling capabilities compare to rectangular waveguide of the same dimension.
•  Also refer Waveguide advantages and disadvantages>> for more information.

WAVEGUIDE RELATED LINKS

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For types of waveguide viz. rectangular & circular, waveguide propagation modes, impedance matching of waveguide read following waveguide tutorial.
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Manufacturers of waveguide components such as waveguide to coaxial adapter, coupler, flanges, gasket, tees, termination, shorts, isolator, circulator, horn antenna, attenuator, feed-thrus, bends, loads, twists, straights, pressure windows, transformers, sliding short circuits, fixed short circuits, sliding mismatches etc. visit following link.
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Rectangular waveguide dimensions as per USA standard including frequency, broad dimension and narrow dimensions, visit following link.
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