Design criteria for bandpass image filters

A design criterion for narrow-band passband image filters is presented based on the distinction between image passband and effective passband. A bandpass image cell with a minimum number of inductances is considered and the impedance and attenuation characteristics of the image cell are investigated. The design of a filter with an attenuation peak in each attenuated band is examined and the nature of attenuation in attenuated bands and in passbands is treated in detail. It is shown that to design an optimal bandpass image filter, it is necessary to know the following data: (1) the type of input and output image impedance; (2) the maximum attenuation in the effective passband; (3) the width of the effective passband; and (4) the minimum attenuation in the attenuating bands.