Highly compact wideband double-section rat-race hybrid with harmonic suppression using series and shunt stepped impedance transmission lines

Abstract

This paper presents the design of a size miniaturized and harmonic suppressed wideband double-section rat-race coupler (RRC). Series and shunt stepped-impedance transmission line units are proposed to replace the quarter wavelength transmission lines in the conventional design of wideband (50% fractional bandwidth) two-stage rat-race coupler. Design equations are derived using the lossless transmission line model. The proposed double-section RRC occupies only 14% area of the conventional coupler, with good return loss and isolation performances. In addition, the full-wave simulation and measured responses exhibit harmonic suppression up to at least fifth harmonic. The proposed design can be easily implemented using the standard printed circuit board etching process without any via-holes, bonding wires, and lumped elements, which make it very useful for wireless communication systems

A Miniaturized Wideband 3 dB Rat-Race Coupler Utilizing Meander Lines

“…Similarly, for the rat-race coupler [9] employed an artificial transmission line with a size reduction of 78.6% and [10] used T-shape stubs and achieved a size reduction of 70%. In [11] a stepped impedance technique has been adopted to miniaturize the rat-race coupler. The design achieved a fractional bandwidth of 50% with a 86% size reduction but a very complex design.…”

Design of a tri‐band 180‐degree directional coupler with spurious suppression based on extended pi‐shaped microstrip line

“…To face the challenges presented by the wireless communication industry in the current scenario, it is crucial to design microwave components with features such as compactness, harmonic suppression, multifrequency operation, and good out of the band rejection performance. Especially, the design of multiband components is gaining a lot of interest because of their inherent ability to simultaneously operate at different frequencies and thereby saving crucial on‐board space.…”

“…It is often used to design push‐pull amplifiers, balanced networks, beam former, and to achieve circular polarization in antennas . The single band 180‐degree rat‐race couplers have been presented with compactness, harmonic suppression and wide bandwidth for various practical applications. To satisfy the growing demand for multifrequency wireless systems, the designers have exploited various techniques to implement dual/tri/quad‐band RRCs.…”