Suspended substrate stripline structures evaluation for millimeter wave circuits application

Suspended Substrate Stripline (SSS) is a printed circuit technology that can be used for both broadband and narrowband filters in highpass, lowpass, bandpass, bandstop and multiplexer form. It has been widely adopted in a variety of filter designs in the upper microwave and lower millimetre-wave frequency. This paper discusses two methods of designing a suspended substrate stripline bandpass filter. The first method is based on the design equations for the capacitive transmission line filter. The second method is based on the design procedure for broadside-coupled suspended stripline (BCSSS). Investigation has been made so as to determine which of these two methods is a more suitable choice for incorporating into the final finline mixer design operating at 35GHz.