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Purpose This paper aims to present the design of a novel triangular-shaped wideband microstrip bandpass filter implemented on a low-cost substrate with a notched band for interference rejection. Design/methodology/approach The conventional dual-stub filter is embedded with simple fractal-based triangular-circular geometries through various iterations to reject wireless local area network (WLAN) signals with a notched band at 5.8 GHz. Findings The filter covers a wide frequency band from 3.1 to 8.8 GHz and has a fractional bandwidth of 98 per cent with the lower passband of 57.5 per cent and upper passband of 31.6 per cent separated by a notched band at 5.8 GHz. The proposed wideband prototype bandpass filter is fabricated in FR-4 substrate using PCB technology and the simulation results are validated with measurement results which include insertion loss, return loss and group delay. The fabricated filter has a sharp rejection of 28.3 dB at 5.8 GHz. Measured results show good agreement with simulated responses. The performance of the fractal-based wideband filter is compared with other wideband bandpass filters. Originality/value In the proposed work, a fractal-based wideband bandpass filter with a notched band is reported. The conventional dual-stub filter is deployed with triangular-circular geometry to design a wideband filter with a notched band to suppress interference signals at WLAN frequency. The proposed wideband filter exhibits smaller size and better interference rejection compared to other wideband bandpass filter designs implemented on low-cost substrate reported in the literature. The aforementioned wideband filter finds application in wideband wireless communication systems.

A wideband Hilbert fractal stub‐based microstrip bandpass filter with a notched band at 5 GHz on a low‐cost substrate is presented. The proposed filter has a 3 dB fractional bandwidth of 88% from 2.9 to 7.3 GHz, with the lower passband of 43% and upper passband of 32% separated by a notched band. The measured insertion loss of the fabricated filter is less than 1.2 dB in the two passbands of 2.9 to 4.5 GHz and 5.3 to 7.3 GHz. The filter is designed and simulated using full‐wave electromagnetic analysis tool and is validated experimentally. Measured data matches reasonably well with the simulated response. This filter can find applications in any wideband wireless communication devices.

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SummaryThis paper reports the development of a reflectarray (RA) antenna using overlapping tri‐resonance phase distribution to produce enhanced bandwidth performance in X/Ku band frequencies. The RA with square aperture (24 cm) operating from 11 to 15.8 GHz is constructed using unit cells with concentric Malta cross and square ring developed on Diclad substrate isolated from the ground through a 2.5‐mm air layer. Variation in the concentric element's size along with the length of the delay line connected to the square ring offers a 518° phase range. The distribution of the 529 RA elements is done using the phase variations observed at 12, 13, and 14 GHz. The optimized design of the proposed antenna offers a simulated peak gain of 27.43 dBi at 12 GHz and a 1‐dB gain bandwidth of 38%. The experimental validation of the fabricated prototype exhibits a peak gain of 27.4 dBi at 12 GHz with a sidelobe level (SLL), and cross‐polarization level less than −15.6 dB, and −28 dB respectively, and a 1‐dB gain bandwidth of 37%. The enhanced performance characteristics of the proposed X/Ku wideband reflectarray antenna befit the uplink and downlink operations of fixed satellite services (FSS).

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