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A fully printed fractal-perturbed resonant-type composite right/left-handed transmission line (CRLH TL) is proposed with electrically smaller dimensions. The CRLH structure consists of Koch-curve-shaped complementary split ring resonators etched on the ground plane and capacitive gaps embedded in the Koch-curve-shaped conductor line. A generic modelling technique for a set of resonant-type circuits, demonstrated to be extremely useful in the accurate extraction of the circuit elements, has been developed for the first time based on the effective medium concept. With the help of this modelling method, a quarter-wavelength impedance transformer (QIT) made of the CRLH TL is readily synthesised. The full fractal perturbation gives rise to the large lumped circuit elements which predict a significantly lower resonance. To demonstrate possible applications of the CRLH QIT, a Wilkinson power divider is designed, fabricated and measured. A good agreement of S-parameters between simulation and measurement has confirmed not only the design, but also the modelling technique that is of a reference value for characterisation. The engineered divider obtains a 58.9% size reduction and exhibits moderate in-band and out-of-band (isolation) performances in comparison with its conventional counterparts, advancing a step in miniaturisation strategy. [ABSTRACT FROM AUTHOR]

A new resonant-type composite right/left-handed transmission line (CRLH TL) is proposed based on the combination of a complementary single-split ring resonator pair (CSSRRP) etched on the ground plane and a series gap embedded in the conductor strip of a microstrip line. The CSSRRP, which is composed of two identical complementary single-split ring resonators (CSSRR) with face-to-face splits, demonstrates negative permittivity. An equivalent circuit model is presented and studied in depth through the Bloch theory and finally validated by the simulated full-wave S-parameters. The balanced condition for novel CRLH TL is also derived. Moreover, the negative refractive index and backward wave propagation are confirmed by the effective constitutive parameters. It is proved that the zero-degree phase-shift CRLH TL exhibits a significantly lower resonant frequency by constructing the CSSRRP as Koch curves of different iteration order (K-CSSRRP). To demonstrate the applicability, two compact prototype device examples are provided, these being a three-way fork power divider and a four-way series power divider. The three-way divider achieves a 74.2% size reduction and displays comparable performance relative to its conventional counterpart, whereas the four-way divider obtains a 56% bandwidth enhancement and a 48% size reduction in comparison with a conventional one using a one-wavelength meandered transmission line. [ABSTRACT FROM AUTHOR]

A novel composite right/left handed transmission line (CRLH TL) is proposed, for the first time using the Wunderlich-shaped dentiform capacitor and meandered-line short-circuited stub inductor (SSI). The CRLH TL features a larger value of CL and in turn a lower resonance relative to the previous one employing an interdigital capacitor and an SSI. The unique feature of the CRLH TL is applied to engineer a compact Butler matrix. Consistent numerical and measurement results of the matrix prototype centred at 1.8 GHz are shown. The Butler matrix with comparable performance is only 45% of the area that a conventional matrix occupies and can easily facilitate a planar integrated circuit. [ABSTRACT FROM AUTHOR]

A composite right/left-handed transmission line (CRLH TL) and its equivalent circuit model is proposed based on the cascaded complementary single split ring resonator (CCSSRR). The circuit analysis based on Bloch theory is performed to characterise the balanced condition, whereas the constitutive electromagnetic parameters are extracted to demonstrate the negative refractive index (NRI) and propagation constant. The CRLH TL features an enhanced selectivity because an additional transmission zero is introduced in the upper edge of the passband and a relative wide band owing to its intrinsic balance, showing superiority of more flexibility and convenience in the design of novel artificial TLs. [ABSTRACT FROM AUTHOR]

An ultra-wideband (UWB) bandpass filter is presented, with excellent passband performance and improved out-of-band sharpened rejection. It is constructed with Koch island-shaped stepped impedance lines and a composite right/left handed transmission line synthesised by etching a Koch fractal-shaped ring slot in the ground plane and a series capacitive gap in the conductor strip. The equivalent circuit model of the proposed structure is presented and the electrical parameters are also extracted. The UWB filter is designed and implemented to experimentally demonstrate the enhanced performance. Numerical and measurement results show that good performance, such as low return and insertion loss over the UWB passband and sharpened rejection skirts outside the UWB passband, is achieved. Furthermore, the structure is compact in size. [ABSTRACT FROM AUTHOR]