microwave_filter 1.0 Introduction to Filter A filter is a network that provides perfect transmission for all frequencies in certain passband region and infinite attenuation in the stopband regions. Such ideal characteristics cannot be obtained, and the goal of filter design is to approximate the ideal requirements to within an acceptable tolerance. Filters are used in all frequency ranges and are categorized into three main groups: • Low-pass filters that transmit all signals between zero frequency and some upper limit (c and attenuate all frequencies above (c. • High-pass filters that pass all frequencies above the cutoff value (c and reject all frequencies below (c. • Band-pass filters that passes all frequencies in a range (1 to (2 and reject frequencies……