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This study introduces a wide bandwidth and wide axial ratio (AR), circularly polarised (CP), patch array antenna. By combining dual layers of a polarizer with dual layers of linearly polarized microstrip patch antenna, a novel method is created for generating circular polarization waves with a wide frequency range. The dual-layer 2 × 2 and 2 × 8 microstrip patch array antenna is employed to achieve linearly polarized waves and the external polarizer consists of a 3 × 3 and 3 × 12 four-layer dual rings polarizer that transforms linearly polarized (LP) waves into CP waves. The |S11| −10 dB bandwidth of small and large-scale circular polarized array antennas is 20% and 27.06% at 5 GHz, respectively, Simulations and testing show that the 3-dB axial ratio bandwidth (ARBW) at 5 GHz is 17%. The suggested antenna has a lot of potential for satellite communication applications because of its easy structure, wide ARBW, and wide impedance bandwidth. [ABSTRACT FROM AUTHOR]

Two dual-band bandpass filters featuring flexible frequency choice and compact size are proposed using two kinds of resonators.One is based on two pairs of different dimensional slotted ground resonators; another is based on a pair of slotted ground resonators and a microstrip-stepped impedance resonator. Unlike traditional filters, the harmonics of slotted ground resonators forming the lower passband are tuned to higher frequencies; the resonators forming the lower and upper passband lie at the two sides of signal line, the two passbands can be adjusted to the desired values with expected bandwidth by changing the sizes of the resonators independently. The interactions between them are minor. The proposed filters do not need extra impedance matching network unlike traditional dual-band filters and with the ground plane efficiently used, they are more compact in structure. Both filters are optimized with jumping genes evolutionary algorithms for multiobjectives, such as low-insertion loss, suitable bandwidth, and good stopbands. Two optimized bandpass filters were also implemented. Simulation and measurement results are performed to verify their good characteristics. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26028 [ABSTRACT FROM AUTHOR]

A new dual-band bandpass filter featuring flexible frequency choice is proposed.It consists of two resonators out of the two sides of the signal line with different sizes forming two passbands with desired frequency responses and bandwidths. For the resonator forming the lower passband, a shunt resistor is added at the center to make the even mode responses disappear. A wide stopband is obtained between the fundamental and higher odd mode response. So when a smaller resonator is put in the other side of signal line to produce the upper passband, a flexible frequency ratio of two passband can be gotten. The proposed filter is fabricated and measured. Good agreements are obtained between the simulations and measurements. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26030 [ABSTRACT FROM AUTHOR]

In this article, a novel balanced wideband filter based on microstrip coupled lines is proposed. It features characteristics such as wide bandwidth, compact size, and good common-mode suppression. The proposed balanced filter was calculated analytically, simulated by full-wave electromagnetic simulator and validated by the measurements. The calculated, simulated, and measured results are in good agreement with each other. The experimental results show that it can allow the differential-mode signal to be transmitted with low insertion loss across a wide frequency band, whereas the common-mode signal will be well suppressed. The fractional bandwidth of the designed filter is 88%. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1139-1141, 2014 [ABSTRACT FROM AUTHOR]