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A wideband circularly polarized patch antenna is presented in this article. The four‐port antenna is composed of circular patch loaded with four shorting pins and cross‐shaped slot. The realization of wideband benefits from the cooperation of three resonant modes. The lowest mode is due to the resonance of half‐wavelength cross‐shaped slot, while the higher two modes are TM11 mode and TM31 mode of the circular patch, in which the TM31 mode is excited by loading four shorting pins. The L‐shaped probes are utilized to establish the coupling feed mechanism for impedance matching in a wideband range. And the compensation of the radiation null in the broadside direction benefits from the variation of the electric field distribution caused by the shorting pins and the differential L‐shaped feed structure in TM31 mode. For the aim of implementing circularly polarized radiation in the proposed patch configuration, a phase quadrature feed network consisting of power dividers and phase shifters is designed and cooperated with this antenna. In order to verify the design concept, a prototype has been fabricated, assembled and measured. The measured results show that the relative bandwidth of VSWR <1.7 and AR <3 dB is 66.7%, ranging from 2 to 4 GHz. In addition, the measured LHCP gain >3 dBic within 2.01–3.84 GHz, and the fractional bandwidth is 61%. Moreover, the peak gain is 9.9 dBic. [ABSTRACT FROM AUTHOR]

In this article, a new general and effective design method of miniaturized quasi‐lumped‐element wideband filtering phase shifters for integrated RF front‐end is proposed, which is promising in both industrial and academic fields. This wideband filtering phase shifter is built by exploring the multiple different kinds of lumped resonators and arranging them in an easily realizable form with stable performance on the single‐layer substrate using widely accessible and low‐cost PCB processing. In our design, wideband magnitude and phase shift responses with the multiple transmission zeros and small phase deviation are numerically established and obtained. A generalized synthesis method along with theoretical analysis and synthesis curves is proposed to determine its circuit parameters exactly. To verify the proposed design concept and method, two wideband phase shifter prototypes with the different topologies and specifications are implemented and tested. Comparisons of measured and simulated results show good accordance and verify theoretical predictions. These prototypes exhibit attractive features with satisfactory wide bandwidth, high frequency selectivity, small phase deviation, deep and wide stopband, miniaturized size, as well as flexible design freedom, compared to other existing works. [ABSTRACT FROM AUTHOR]

In this paper, a low‐profile and wideband circularly polarized patch antenna using four resonance modes is presented. It is one kind of four‐port antenna implemented by loading five shorting pins on the circular patch. In order to achieve wideband properties, TM11 and TM22 modes are stimulated in circular patch, along with their polarization orthogonal modes (TM11+ and TM22+ modes). The TM11+ mode is excited by the Γ‐shaped feed, while the TM22 mode and TM22+ mode is stimulated by four shorting pins in close proximity to the Γ‐shaped feed. Due to the strong coupling between shorting pins and Γ‐shaped feed, the peak electric field generated on the two opposing shorting pins causes the magnetic current density on the circumference of the patch to be changed, which in turn leads to the realization of broadside radiation in the TM22 and TM22+ modes. In addition, the function of the shorting pin loaded in the center of the patch is to improve the impedance matching when TM22 and TM22+ modes are operated. Cooperated with the devised one‐to‐four feed network with equal amplitude and progressive phase difference of 90°, the wideband circularly polarized patch antenna is obtained. To verify this design concept, a prototype is fabricated and measured. The diameter of the patch is 0.68λ0 and the profile is 0.078λ0 (λ0 is the wavelength in the free space at the center frequency). The measured relative bandwidth of VSWR < 2 is 106%, involving 1.53–4.96 GHz, while that of AR < 3 dB is 98%, ranging from 1.54 to 4.48 GHz. Besides, the measured LHCP gain > 3 dBic in the frequency band of 1.48–4.42 GHz. [ABSTRACT FROM AUTHOR]

ABSTRACT Tuning space mapping (TSM) with tuning exponent parameter of T-matrix is proposed. A section of design interest in the electromagnetic (EM) model is replaced by ' n' pieces cascaded T-matrixes, and each T-matrix is the EM-simulated T-parameter of preassigned unit cell circuit (PUCC). Finally the optimal exponent parameter of T-matrix is transferred to original design variables. The proposed TSM not only inherits the advantages of circuit tuning element-less (CTEL) TSM in prior art but also overcome the number range limitation that the tuning parameter must be positive for tuning in CTEL TSM. The proposed method has the minimal specification error and lowest simulation time comparing with other TSM methods. Verification examples, comparisons and discussions are also implemented. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:232-239, 2016. [ABSTRACT FROM AUTHOR]

ABSTRACT A new all-pass filter (APF) is proposed. The APF is based on a symmetrical ring, consisting of four sections of transmission line, which are identical in electrical length, different in characteristic impedance. Two input/output ports are connected orthogonally to the ring. The APF is analyzed by using the odd-even model, and the all-pass condition is then theoretically obtained. Meeting the condition, the circuit is all-pass in frequency, but nonlinear in transmission phase. The nonlinear transmission phase with frequency may be adjusted by changing the lines' impedances, while remaining the all-pass property. Then the APF is used to design a wideband 90° differential phase shifter with adjustable bandwidth. Samples are designed, fabricated and measured. Good agreements are achieved among the theoretic, numerical and experimental results. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:191-195, 2014. [ABSTRACT FROM AUTHOR]