Gheorghe Sajin

Magnetostatic wave transducers on silicon wafers and on silicon membranes

The paper presents the design, realisation and experiments of MSW launchers and detectors made on silicon wafers and silicon membranes. S parameters measurement on ferrite unloaded and on magnetised ferrite loaded structures demonstrates the feasibility of such transducer. Using the silicon membranes to support these devices offers the advantage of miniaturisation, with important openings toward microwave circuit integration on semiconductor substrate.

Silicon resonating antenna based on CPW composite right/left-handed transmission line

The aim of this paper is to present results obtained in modeling, technological realization and measurements for a CPW (CoPlanar Waveguide) zeroth-order resonating antenna, based on CRLH (composite right/left-handed) transmission line. The CRLH consists of series connected CPW interdigital capacitors and two parallel connected CPW transmission lines. The antenna was fabricated on silicon substrate for a subsequent integration in a more complex circuit. A very good agreement between the experimental and simulation results has been observed for return-loss as well as for the radiation pattern.

Tuning ferrite supported antenna with CRLH cells

This paper presents the results in frequncy tuning of a ferrite supported resonating CPW antenna based on CRLH (Composite Right/Left-Handed) transmission lines. The tuning is obtained by magnetically polarizing the ferrite substrate with a magnetic biasing field variable between 0 T and 0.26 T. Data obtained by simulation with a suitable microwave software indicate a frequency shift of 530 MHz at a working frequency 12.88 GHz, in very good agreement with the experimental results showing a frequency shift of 450 MHz

Magnetic scanning of the radiation characteristic of a CRLH CPW antenna

The paper presents the results concerning the radiation characteristic scanning of a ferrite supported resonating CPW antenna based on CRLH (Composite Right / Left-Handed) transmission lines. The scanning effect is obtained by magnetically polarizing the ferrite substrate. Data obtained by simulation with a suitable microwave software indicate an azimuthal characteristic deviation of ± 9.780 at a working frequency f = 13 GHz for a variable magnetic biasing field between 0 T and 0.16 T. This result is in very good agreement with the experimental data showing a characteristic displacement of +120 … −100.

Scanning radiation characteristic of a CRLH CPW ferrite supported antenna

The paper deals with the radiation characteristic scanning of a ferrite supported resonating CPW antenna based on CRLH (Composite Right/Left-Handed) transmission lines. The scanning effect is obtained by magnetically polarizing the ferrite substrate with a magnetic biasing field which varies between 0 T and 0.16 T. Data obtained by simulation with a suitable microwave software indicate an azimuthally characteristic deviation of ± 9.87° at a working frequency of 13 GHz, in very good agreement with the experimental results showing an azimuthally characteristic deviation of 10°.

Metamaterial millimeter wave directional coupler on silicon substrate

This paper presents the design and manufacturing of a metamaterial Composite Right/Left Handed (CRLH) directional coupler on silicon substrate in coplanar waveguide (CPW) configuration, with a frequency band between 26–28 GHz. The design makes use of 4 CRLH cells, cascaded and coupled two by two in order to obtain the directional coupler structure. The device was processed on a 500µm thick silicon substrate with a Au/Cr metallization with the purpose of easy integration in more complex millimeter wave integrated circuits. The measurement of working frequency, reflection loss and isolation of the coupler validates the calculated values of these parameters.

On-wafer experimental characterization for a 4-port circuit, using a two-port Vector Network Analyzer

The paper presents an experimental method useful to characterize a four-port circuit, using a two-port VNA (vector network analyzer). As an example, the method is applied for a coupler. The results obtained by using this method and the expected results obtained by simulation are in good agreement.

Frequency doubler and short pulse generator, based on nonlinear composite right/left-handed transmission line

A new topology of balanced NL CRLH TL has been designed and then analysed, using hyperabrupt Schottky-varactor diodes as nonlinear element. The parallel resonators of the CRLH structures have been modelled by open-ended transmission lines, to overcome the biasing problems of the diodes. For a NL CRLH TL consisting of three identical cascaded cells, the numerical put into evidence the possibility the possibility to use it as frequency doubler (5 dB conversion losses) and short pulse generator (the width of the output pulse is two times shorter comparing to the pulse width of the equivalent input pulse).

Magnetically tuned CRLH CPW zeroth order antenna

This paper presents the results in frequency tuning of a CPW antenna based on CRLH (Composite Right/Left-Handed) transmission lines. In order to be tuned, the antenna was made on a ferrite substrate. The tuning is obtained by magnetically biasing this ferrite substrate with a magnetic biasing field variable between 0 T and 0.26 T. Data obtained by simulation with a suitable microwave software indicate a frequency shift of 530 MHz at a working frequency of 12.88 GHz, in very good agreement with the experimental results showing a frequency shift of 450 MHz.

Spectral and time domain characteristics of nonlinear magnetostatic surface waves in pulsed regime

In this paper, the excitation of microwave nonlinear magnetostatic surface wave (MSSW) in delay line configurations is discussed The theory as well as the obtained experimental results confirm the possibility for the propagation of solitonic MSSCVs in grounded MSSW delay lines. Actually, the non-linear term of MSSWs is always negative, and the Lighthill criterion is fulfilled in well defined frequency ranges, where the ground plane provides an inversion in the disperion properties of the device. Outside that range, nonlinear MSSWs or dark solitons can be excited. All of these phenomena are characterized by quite different spectral and time domain responses. Applications of the nonlinear MSSWs in pulsed regime can be found in the pulse compression and solitonic signal processing by using the delay line as a feedback network in an oscillator configuration.