This paper proposes a novel miniaturization technique of quarter-wave transformers (QWTs), implemented using multi-section transmission lines (MSTLs), based on the quarter-wave-like transformer (QWLT) theory. Multi-section QWLT characteristics are derived analytically and solved via appropriate optimization algorithms for associated transmission-line parameters. For an illustration purpose, two-and three-section QWLT prototypes with 50% physical size reduction from the corresponding QWT size operating at 2.4 GHz are fabricated using microstrips and tested. It is found that these prototypes yield acceptable return loss at 2.4 GHz without significant bandwidth reduction, comparing to the QWT result.
This paper proposes a novel technique to miniaturize the size of any reactance-to-reactance transformers (RRTs). These transformers are designed based on conjugately characteristic-impedance transmission lines (CCITLs)and Meta-Smith charts (MSCs). Note that the proposed technique can be effectively applied to popular microwave circuits; i.e., open-circuited and short-circuited tuning stubs as special cases. Numerical results are calculated, analyzed and compared with those of conventional stubs. In addition, the RRT prototype based on CCITLs is designed, simulated and measured to verify the proposed technique. It is found that the properly designed RRT prototype based on CCITLs can provide shorter electrical and physical lengths than those of the conventional RRT prototype indeed.
Recently, the magnetoelectric (ME) effect is widely studied to apply in sensing applications. This paper proposes the investigation of ME effect in the bi-layer plate structure, which is the structure that allows deformation in the thickness direction. Mathematical models of the ME coefficients are developed using the constitutive equations of magnetostrictive and piezoelectric. Two modes of interest include longitudinal-transverse (L-T) and transverse-transverse (T-T) modes. Applying the models to the nanolayer of Terfenol-D/PZT in the assumingly low frequency regime yields the optimal thickness ratio of 0.34 for both modes. The maximum ME coefficients for 5, 10, and 10 nm thick structures are equal but occur at different resonant frequencies. They are approximately 480 and 240 mV/Oe cm for T-T and L-T modes, respectively. The maximum ME coefficients of the Terfenol-D/PZT plate structure are sufficiently high for nanoscale magnetic sensing applications.
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