A novel via-free microstrip balanced-to-balanced diplexer for narrow-band applications

Abstract

In this article, a new type of microstrip vias‐free balanced‐to‐balanced diplexer suitable for narrow‐band applications is presented. The structure of the balanced diplexer is based on two balanced bandpass filters designed for f1=1.1 GHz and f2=1.8 GHz and two transmission lines used to satisfy the open circuit conditions required in the diplexer's design. This diplexer exhibits good common‐mode rejection ratio better than 40 dB at the passbands. The attenuation is better than 35 dB at the rejection bands. The isolation between output ports is better than 50 dB. Simulated and experimental results are compared with good agreement. The diplexer is easy of fabricate and integrate with others planar balanced devices. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:567–570, 2015

Compact Microstrip Balanced-to-Balanced Diplexer Using Stub-Loaded Triple-Mode Resonators

“…Nevertheless, the circuits with T-junction occupy large circuit areas obviously. To reduce the size of communication system, some balanced diplexers without T-junctions have been studied [7][8][9][10]. Zhou et al [8] proposed a balanced diplexer with uniform impedance resonators and short-ended microstrip parallel-coupling feedlines.…”

“…In addition, with dual-open/short-stub loaded resonator, Wei Jiang et al designed a quad-channel diplexer [9], but it was only suitable for narrow-band application. By applying 16 close loops, a via-free and compact diplexer was proposed in [10]. However, both the return losses and insertion losses were poor.…”

Planar Differential Filtenna for Communications

“…Crosstalk is generated by the coupling of lines within the circuit, whereas EMI is caused by external electromagnetic energy coupled to the system [8][9][10]. Differential circuits, including filtennas, are a well-known technique to increase immunity to these effects [11][12][13][14][15]. In [16], a 2-pole filtering antenna is presented; however, no experimental CM and DM radiation patterns are shown.…”

Planar common‐mode suppression network in balanced structures

“…Their advantages in comparison with single‐ended circuits: higher immunity to external electromagnetic interference (EMI), reduced electromagnetic radiation over adjacent circuits, and lower currents on ground plane, are some of the main reasons for this. Consequently, multiple balanced structures like antennas, diplexers and filters, have been recently subject of investigation .…”

“…In addition, surface mount devices are needed, increasing fabrication complexity. Finally, although loading a circuit with a λ g /4 open stub to produce a transmission zero is a known technique in filter design , the application of methods using this principle in the area of balanced devices is limited.…”