Phase Shifter and types
A phase shifter is two port passive device. It produces a variable change in phase of transmitted wave passing through it. It is realized by placing a lossless dielectric slab within a waveguide parallel to and at the maximum E field position. The dielectric slab is tapered at both the ends to reduce reflections. There are various types of phase shifters which include Precision phase shifter, MIC phase shifter,Reciprocal and Non-reciprocal phase shifter.
A differential phase change is produced due to change of wave velocity through slab. As shown in the figure,
by adjusting the length L, different phase shifts can be produced. S matrix of the ideal phase shifter is as follows.
| 0 e-jΔΦ |
| e-jΔΦ 0 |
Precision Phase shifter
Precision Phase shifter can be designed as rotary type. It is made of following parts:
• Both the ends circular to rectangular waveguide transitions
• Circular waveguide with lossless dielectric plate of half wave length (180 degree) at the Middle
• Between waveguide transition and above half wave plate, there are plates of quarter lenth(90 degree)
TE10 mode of rectangular waveguide becomes TE11 after passing through the transition at the end. Appropriate phase shift is obtained after wave goes through the two quarter sections provided at the ends and also rotary half wave section available in the middle.
MIC phase shifter
MIC phase shifter is constructed using ferrite material.
Ferrite materials possess dielectric constant of about 9-16 and loss tangent of less than 0.001.
By varying magnitude and direction of static magnetic field propagation constant of the E-M waves can be changed.
This is the base of the MIC phase shifter.
Ferrite phase shifters are mainly of two types reciprocal and non-reciprocal. There are analog and digital categories under each of this type of phase shifter. In the analog version, phase is controlled by varying either magnitude or direction of magnetisation vector using applied magnetic field(static).
In the digital version, phase is controlled by using ferrite material of high remanence by latching dielectric substrate using current pulse to chan direction of DC magnetic field.
WAVEGUIDE RELATED LINKS
RF Switch basics and applications along with manufacturers of RF switch refer following link:
For types of waveguide viz. rectangular & circular, waveguide propagation modes, impedance matching of waveguide read following waveguide tutorial.
waveguide basics tutorial
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.
Waveguide components manufacturer
Rectangular waveguide dimensions as per USA standard including frequency, broad dimension and narrow dimensions, visit following link.
Waveguide dimensions table
This article describes microstrip line basics and mention types of microstrip lines and their advantages. READ MORE.
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