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An analogue phase shifter with a constant low insertion loss (IL) and compact size is proposed. It consists of two quarter wavelength transmission lines and three tunable reflective loads. The theoretical analysis to maximise the relative phase shift, reduce the IL and the IL variation of the phase shifter is presented explicitly, which provides performance estimation and design guidance for this class phase shifter. A circuit with a size of 0.12λg × 0.21λg is designed and fabricated to verify the theory. The simulated and measured results are in good agreement. The measurement shows that the relative phase shift of the proposed phase shifter is 186° at 1.97 GHz. The average IL is 0.79 dB with a very small IL variation which is just 0.02 dB. [ABSTRACT FROM AUTHOR]

A modulatable electromagnetically induced transparency (EIT) is achieved using a slotted circle ring structure. The circle ring structure is used to induce a polarisation-independence resonance with a low Q factor, while the slot is etched to obtain a polarisation-dependence resonance with a high Q factor. The EIT effect is obtained when the two resonances have nearby resonant frequencies but with different Q factors. As both resonant modes are excited by the external field independently, different coupling strength is achieved simply by adjusting the polarisation angle. Then the transmission of EIT is successfully modulated. The design concept is well validated both by simulation and measurement. [ABSTRACT FROM AUTHOR]