The development of wide-band of bandpass filter of C-band using parallel coupled-line method for RF SAR system

This manuscript proposes the numerical design of a Parallel Coupled-line bandpass filter that will be used as part of the RF for the SAR imaging mission of the Medium Altitude Long Endurance-Unmanned Aerial Vehicle (MALE-UAV), with its signal frequency at C-band. A bandpass filter was built on an NPC H220 substrate with a dielectric constant (r) of 1.27, a thickness of 1.6 mm, and a dissipation factor (tan δ) of 0.0005. The filter was designed to operate at a central frequency of approximately 5.3 GHz, with lower and upper cut-off frequencies of 5 and 5.6 GHz, respectively. For the design, a Chebyshev prototype with 0.5 dB passband ripple and fifth order is chosen. The performance of the filter simulation at 5.3 GHz center frequencies demonstrated that the return loss S (2,2) is around -14.302 dB and also the insertion loss S (2,1) is around -0.646 dB. For the performance of filter fabrication showed the return loss S (2,2) is around -11.55 dB and for the insertion loss S (2,1) is around -2.551 dB. The simulation and fabrication result could meet the minimum requirement at the center frequency. The bandwidth width has unmet the minimum requirement, so it needs improvement during the next fabrication.