A Bandpass Filter Using Edge Coupled and Direct Coupled Techniques

Coupled resonators are commonly used in the design of filters with bandpass response. Majority of these filters are designed using edge coupled or direct coupled technique. This paper proposes the implementation of the edge coupled and the direct coupled technique in the designing of a bandpass filter using microstrip technology. This is to ease the bandwidth and the frequency control of the circuit. The bandpass filter is designed to operate at a centre frequency of 1.95 GHz, using the open-loop resonators for the ease of edge coupling and a λ/4 resonator for the direct coupling. The measured response of the prototyped design and the simulated response show good agreements between the two.