This paper presents the design and microfabrication of a coaxial dual model filter for applications in LMDS systems. The coaxial structure is formed by five conductive layers, each of which is of 700 µm thickness. The filter uses an air filled coaxial transmission line. It is compact with low dispersion and low loss. The design has been extensively tested using a prototype filter micromachined using laser drilling on a copper sheet and the results show a good agreement with the theoretical calculations. The laser fabrication has exposed weakness in suitability to volume production, uneven edges and oxide residuals on the edges, which affects the filter performance. A process for fabrication of such a filter in SU-8 has been developed which is based on a UV lithographical process. In order to fabricate such thick SU-8 layers, the SU-8 process has been optimized in terms of UV radiation and post exposure baking. During the test fabrication, the optimized SU-8 process has produced microstructures with an aspect ratio of 40:1 and a sidewall of 90 ± 0.1 • . The high quality SU-8 structures can be then either coated with a conductive metal or used as moulds for producing copper structures using an electroforming process. The microfabrication process presented in this paper suits the proposed filter well. It also reveals a good potential for volume production of high quality RF devices.
A Reconfigurable Frequency Measurement (RFM) device operating from 1 to 4 GHz has been designed, simulated, fabricated and tested. The RFM device can identify an unknown signal by assigning it to one of the four sub-bands defined by a switched circuit. The 2-bit design is formed by switching between two branches, where each branch corresponds to one bit. The RFM device is made using PIN diodes and other surface mounted components, integrated on the same dielectric substrate in microstrip technology. Simulated and measured results are shown with a very good agreement.
Surface plasmon resonance (SPR) based sensors are usually designed using the Kretschmann prism coupling configuration in which an input beam couples with a surface plasmon through a thin metal film. This is generally preferred by sensor developers for building planar devices instead of the Otto prism coupling configuration, which, for efficient coupling, requires the metal surface to be maintained at a distance on the order of the wavelength from the input prism surface. In this paper, we report on the microfabrication and characterization of an Otto chip device, which is suitable for applications of the SPR effect in gas sensing and biosensing.
A new compact Reconfigurable Frequency Measurement (RFM) device, based on interferometry is presented in this paper. The device combines the advantages of reconfigurability and fractal geometry. The interferometer uses a Wilkinson power divider connected to two microstrip delay lines; one of these corresponds to the second iteration of the Hilbert fractal curve. PIN diode switches are properly placed in the fractal delay line to achieve a 3-bit circuit, which operates in the 2.7-4.5 GHz range. The design and simulations presented are done using a full wave EM simulator, and the frequency responses of the circuit are then shown and compared to measured results.
This paper presents a building block approach to design a reconfigurable discriminator (RD), which is the core circuit in frequency identification receivers. The RD is used to identify an unknown signal; the output of the circuit determines a frequency subband where the unknown signal falls into. The proposed building block design approach is scalable and can be used to produce any multibit RD. This design approach can be used to produce RD circuits with more or less resolution for a fixed band of operation, according to the number of bits used for a given design. The building block approach is demonstrated through the design of a 4‐bit RD. This design is a two‐port device that provides a series readout and can produce 4 bits for frequency identification. The device operates from 1 to 4 GHz, implemented by microstrip lines and PIN diode switches. Simulated and measured responses are in agreement.
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