Abstract
This paper has designed a bandpass filter using a coplanar stripline
stub (CPS) resonator consisting of open and short-ended strip lines
connected to the PIN Diode switches. The use of spurline stub resonators
inside CPS results in bandpass and bandstop filters, depending on the
PIN diode switch configurations. The work presents a novel circuit
architecture aimed at reducing parasitic resonance of the spurline
resonators and acquire the necessary series stub characteristics. The
proposed filter resonates at 6.9-9 GHz and 1.7-4.7 GHz, and 8.4 GHz when
the PIN diodes are forward and reverse-biased, respectively. It also
resonates at 1-2.1 GHz, 4.8-5.3 GHz, and 6.9-9 GHz when one diode is
reverse-biased, and the other is connected in forward bias. An insertion
loss below -0.55 dB and a return loss less than 10dB have been obtained
during simulation and measurement. The designed filter can find
different applications for the 1.8 GHz GSM band, 2.4/5.8GHz (WLAN), 3.6
GHz (WiMAX), Long Term Evolution (LTE), and WIFI. The filter can be used
in various multi-frequency systems owing to its compact size. The
measured and simulated findings of the proposed CPS spurline stub
resonator wideband bandpass filters are substantially consistent.