A small introduction of Impatt diodes is presented. Then the measurement of impedences are taken at different frequencies and are compared. For comparison a noise figure of 20dB is taken into consideration. The area of diode taken is 10^-4 cm^2. The input power given is 50000 watts per square cm. At the end , graphs are plotted showing the variations. From the graph we can say the variation of impedances with various parameters and from the we can get an idea about noise.