No abstract

Articles you may be interested inThick membrane operated rf microelectromechanical system switch with low actuation voltage A novel microwave microelectromechanical systems switch with a coplanar waveguide structure has been developed. The switch consists of a freestanding metallic cantilever and an electromagnet. A permanent magnetic film was deposited on top of the cantilever. By supplying a dc current to the electromagnet, the magnetic field generated would attract or repel the permanent magnetic film on top of the cantilever, causing it to make or break contact with a bottom electrode. An all-electrodeposition method has been used to improve the mechanical properties of the cantilever. The deposition process of the cantilevers has been optimized to improve the adhesion of the cantilever to the substrate and to minimize the switching dc power. Using commercially available electromagnet, a voltage of 2 V ͑dc power of about 15 mW͒, is sufficient to actuate the switches. Similar switching power was observed using an improved hand wound electromagnet. The on-state dc resistance of the switches is generally less than 2 ⍀. At 10 GHz, the on state insertion loss due purely to the switches is about 0.1 dB and off state isolation is greater than 20 dB. Repeated operations of the switches showed no sign of performance degradation in a conventional room environment.

A novel construction of microwave switchable lowpass filter based on electromagnetic bandgap (EBG) and cadmium sulfide (CdS) thin film is proposed. Linearly tapered slot‐array EBG structure is well known for its exceptional stopband ability and compact physical size. When the illumination‐sensitive CdS thin film is deposited on the perforations of the EBG structure, the stopband phenomenon induced by tapered slot‐array can be controlled by optical means. Innovative “conductive islands” were introduced to reside in the center of each perforation in order to enhance the optical switching. It has been demonstrated in both simulation and experimental measurement that the transmission coefficient is switched from 31.3 to 5.6 dB at 13 GHz when the gap width between the conductive island and the perforation is 30 μm. As the gap width decreases, the insertion loss can be reduced. Simulation result indicates that the insertion loss can be improved to around 1 dB at 13 GHz when the gap width is decreased to 5 μm. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2238–2242, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22665

A new design of wideband microwave bandpass filter based on intercoupled split‐ring resonator is proposed. The split‐ring resonator structure is well‐know for its unique resonance feature that exhibit a negative permeability. By implementing the split‐ring resonator directly on a microstrip transmission line, a bandpass filter with a large fractional bandwidth has been achieved. The novel periodic intercoupled split‐ring resonator bandpass filter is compatible with microwave planar technology and the passband region is controllable. The filter design has been validated and demonstrated in both simulations and experimental measurements. A bandpass filter with a fractional bandwidth of 50% at a center frequency of 14 GHz was achieved with a maximum insertion loss of 0.75 dB in the passband region. Meanwhile, the fractional bandwidth has been demonstrated to be controllable and this was reduced to 37% by sacrificing the periodicity of the intercoupled split‐ring resonator structure. Therefore, the flexible characteristics and the simple implementation method may render the proposed filter to be very useful in many frequency‐selective and oscillation‐suppression applications. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1809–1813, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22588

Articles you may be interested inSquare-shaped metal screens in the infrared to terahertz spectral region: Resonance frequency, band gap, and bandpass filter characteristics J. Appl. Phys.A photonic band-gap resonator to facilitate GHz-frequency conductivity experiments in pulsed magnetic fields Rev. Sci. Instrum. 77, 084702 (2006); 10.1063/1.2336761 Studies of surface two-dimensional photonic band-gap structuresMicrowave photonic band-gap ͑PBG͒ structures are well known for their superior ability to generate a band stop effect at a certain frequency range. Together with the microstrip transmission line structure, PBG can be utilized as a filter exceptionally well since the periodic perforation patterns can be implemented easily in the ground plane. In this research work, square perforations of different dimensions are constructed in the ground plane of a microstrip transmission line to achieve a double band stop PBG structure. Thus, the transmission ability of the microstrip line is being blocked at different frequency ranges to create a bandpass filter. It is found that the bandpass frequency is strongly dependent on the dimension to period distance ratio. It is demonstrated in both simulation and measurement that the bandpass region can be created at high frequency above 10 GHz.