15-06-2012, 12:50 PM
To measure frequency of microwave source and demonstrate relationship among guide dimensions, free space wave length and guide wavelength
frequency of microwave source and demonstrate .docx (Size: 34.02 KB / Downloads: 30)
EQUIPMENT REQUIRED:
Klystron tube, Klystron power supply, Klystron mount, isolator, frequency meter, variable attenuator, slotted section, tunable probe, VSWR Meter, Waveguide stand, movable short/matched termination.
THEORY:
The cut-off frequency relationship shows that the physical size of the wave guide will determine the propagation of the particular modes of specific orders determined by values of m and n. The minimum cut-off frequency is obtained for a rectangular wave guide having dimension a>b, for values of m=1, n=0, i.e. TE10 mode is the dominant mode since for TMmn modes, n#0 or n#0 the lowest-order mode possible is TE10, called the dominant mode in a rectangular wave guide for a>b.
PROCEDURE:
1. Set up the components and equipments as shown in figure.
2. Set up variable attenuator at minimum attenuation position.
3. Keep the control knobs of klystron power supply as below:
Beam voltage – OFF
Mod-switch – AM
Beam voltage knob – Fully anti clock wise
Repeller voltage – Fully clock wise
AM – Amplitude knob – Around fully clock wise
AM – Frequency knob – Around mid position
4. Switch ‘ON’ the klystron power supply, CRO and cooling fan switch.
5. Switch ’ON’ the beam voltage switch and set beam voltage at 300V with help of beam voltage knob.
6. Adjust the repeller voltage to get the maximum amplitude in CRO
7. Maximize the amplitude with AM amplitude and frequency control knob of power supply.