A simple and nonexpensive adapted dip-coating technique is presented and used to fabricate arrays of magnetic nanowires with a linear varying height profile. This approach allows controlling the wire height from tenths of nanometers up to several micrometers. Furthermore, the main parameters of this height gradient can be controlled, such as the maximum wire height and the lateral span of the wire array, which can be predicted with excellent accuracy using a proposed analytical model. Moreover, we show that by sequential electrodeposition with dip-coating, arrays of these height varying wires can be grown. This technique represents a novel method to fill porous templates with controlled spatial growth, leading to the fabrication of novel structures and providing control over structural features on the nanoscale level. In particular, the use of these asymmetrically loaded magnetic nanowired substrates to obtain improved microwave nonreciprocal behavior is shown for a microwave phase shifter.

Electrodeposition Growth of Nanowire Arrays with Height Gradient Profiles for Microwave Device Applications

Nonreciprocal microstrip lines based on magnetic nanowired substrates were fabricated for the characterization of microwave differential phase shifts. We provide a fully integrated solution for the nonreciprocal edge guided mode, which is achieved by asymmetrically loading the width of the microstrip with nanowires of different heights. An analytical model explaining the microwave nonreciprocal propagation, which takes into account the substrate permittivity and the microstrip memductance, is validated with the experiment.

Differential phase shift in nonreciprocal microstrip lines on magnetic nanowired substrates

Magnetic nanowired substrates (MNWS) have been used for the fabrication of a planar nonreciprocal microstrip device. It shows a differential phase shift of 300 degrees cm-1 at K a -band without requiring the application of a dc bias magnetic field, and making it suitable for miniaturized gyrator applications. The nonreciprocal operation is achieved by loading the device with nanowires of different ferromagnetic materials. This allows to control the phase velocity of the microwave signal passing through the device by virtue of the spatial variation of the MNWS permeability. The measured microwave performances of the device have been reproduced with excellent accuracy using a proposed analytical model based on an effective medium theory and useful for the prediction of further tunable capabilities.

/pdf/self-biased-nonreciprocal-microstrip-phase-shifter-on-2qb7uzalg8.pdf

Self-Biased Nonreciprocal Microstrip Phase Shifter on Magnetic Nanowired Substrate Suitable for Gyrator Applications

In this paper, we present a phase-adjustment technique of the digital-latching ferrite phase shifter. The pertubation approach is used here. The experimental results agree well with the theoretical ones.

Phase-adjustment technique of the digital-latching ferrite phase shifter

In this paper, an improved design of a broad-band latching ferrite phase shifter in grooved waveguide is discussed. The elimination technique for the insertion-loss peak is also introduced. The little gaps between the metal bars and waveguide wall are beneficial to suppress the high-order modes caused by the filling of high constant dielectric in the ferrite toroid. The theoretical and measured results have shown that the changes in differential phase shift with frequency remains less than 2.2%; the insertion loss and voltage standing-wave ratio of the device are good over the band 2/spl sim/4 GHz.

Improved design of broad-band latching ferrite phase shifter in a reduced-size grooved waveguide

In this paper, the transcendental equations for twin ferrite toroidal grooved waveguide shifters are given. With typical parameters, the differential phase shift, the insertion loss and the sizes of the /spl lambda//sub g//4 impedance transformer are calculated. The results show that the figure of merit and the differential phase shift of the phase shifter are larger than those of rectangular waveguide phase shifter under the same condition. To prove the equations given in the paper, phase shifts are measured by experiments. The results are basically in agreement with those calculated by given equations. >

Mei-Juan Shi

Papers

Analysis of twin ferrite toroidal phase shifter in grooved waveguide