Montgomery, Techniques of Microwave Measurements, McGraw-Hill, New York, 1947.ĥ. Annapurna Das, Sisir K Das, Microwave Engineering, McGraw-Hill International Edition, Singapore, 2000.Ĥ. Ginzton: Microwave Measurements, McGraw-Hill Book Company, Inc. VanDuzer, Fields and Waves in Communication Electronics, Third Edition, John Wiley & Sons, 1994.Ģ. The smith chart calculations and the transmission line equation calculations for impedance are valid under what mode conditions?ġ. Explain qualitatively the impedance variation with the depth of screw and with frequency?Ģ. That can be matched with the chosen one.ġ. The resistance and reactance for the unknown impedance can be seen in the visible tabs. Now press the “ Value of Unknown Impedance” button.ĩ. Fix the value of VSWR by pressing “ VSWR value of unknown impedance”. Again find the first minima for load condition by using slider and fix it by pressing the button “ First minima from load (Unknown Impedance)”.Ĩ. Use toggle button to switch to “ Load” mode.ħ. Fix the first minima by clicking “ First minima from load (Short Circuited)” and second minima by clicking “ Second minima from load (Short Circuited)”.Ħ. Find first and second minima by using slider. Use toggle button to select between “ Short Circuit” and other “ load”. We can vary the resistance and reactance of load by using sliders in case of “ Unmatched Load”.Ĥ. Choose “ Unmatched Load” to perform the experiment from the Loads given in Loads window. Hence we are using distance of minima to find the impedance.ģ. Realizing a screw whose reactance vary with insertion is not feasible. matched load, short circuit, open circuit and unmatched load are used here. Select “ Forward direction” in isolator and adjust the attenuation using slider.Ģ. Fix the modulator frequency using slider. Fix the frequency and amplitude of the source with the help of slider and knob. Experimental arrangement for measuring impedanceġ. The unknown impedance can also be determined by using chart, once the VSWR and position of minima is known with the load.įig 1. Where b is the susceptance due to the screw. The depth of screw, changes only the reactive part of the admittance, so if the line is matched, the load offered by the screw for a certain depth is The unknown load admittances is given by the transmission equation asĭ,min = distance of first minima from the load.Ī screw projecting into the waveguide offers variation in the admittance with the insertion of the screw. Normally for distance measurement minima is used because it is more sharply defined. The unknown terminating impedance can be determined by measuring standing wave ratio & distance of a convenient maxima or minima from the load. Microwave source with square wave modulation Objective: To determine the impedance of the given load.ġ.
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