Lidan Yao

A novel three-dimensional dual-band balun with frequency-independent phase difference and complete ground

A novel three-dimensional (3D) dual-band balun employing the double-sided parallel-strip line (DSPSL) with inherent impedance-transforming capability and complete ground is presented in this paper. The proposed balun is mainly composed of two mutually perpendicular printed circuit boards (PCBs), one of which is a horizontal feeding plane with a slender slot and the other of which is a mounted board vertical to the former. An unbalanced input port and two balanced output ports are totally located at the feeding plane. Utilising the configuration of DSPSL, two different dual-band impedance transformers of two sections are placed in the top and bottom layers of the vertical mounted board respectively. Thus, the transformers are applicable to transform impedances at two frequencies simultaneously. Furthermore, the 180° phase difference is frequency-independent, which facilitates the broadband operation. For verification, two numerical examples with different frequency ratios are designed and simulated, one of which is fabricated on a Rogers 4350B board. Both the simulated and measured results exhibit excellent performance and agree well with each other. In essence, this 3D balun is comprised of a single-layer planar circuit configuration. Consequently, owing to easy integration and low cost, it will be widely applied in the balanced radio frequency components.

An independently reconfigurable dual-mode dual-band substrate integrated waveguide filter

In this paper, a novel perturbation approach for implementing the independently reconfigurable dual-mode dual-band substrate integrated waveguide (SIW) filter is proposed. Dual-frequency manipulation is achieved by adding perturbation via-holes (the first variable) and changing the lengths of the interference slot (the second variable) in each cavity. The independent control of the upper passband only depends on the second variable while the lower passband is independently tuned by combining the two variables. Using such a design method, a two-cavity dual-band SIW filter is designed and experimentally assessed with four via-holes and an interference slot in each cavity. The dual-band filter not only has a frequency ratio (fR) ranging from 1.14 to 1.58 but also can be considered as a single passband one with a tunable range of 40.5% from 1.26 GHz to 2.12 GHz. The scattering parameters |S11| and |S21| are in the range of -10.72 dB to -37.17 dB and -3.67 dB to -7.22 dB in the operating dual bands, respectively. All the simulated and measured results show an acceptable agreement with the predicted data.

A wide-band 180-degree phase shifter using a pair of coupled-line stubs

Based on a pair of stubs and a coupled-line section, an out-of-phase phase shifter for wide-band application is proposed in this paper. The typical electrical parameters and numerical verifications are presented. This proposed 180-degree phase shifter features single-layer PCB fabrication with complete ground, wide phase-shifting bandwidth, wide impedance-matching bandwidth, and a simple circuit structure.