SU-8 Ka-band filter and microfabrication

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

Filtros para un cabezal de comunicaciones entre vehículos

In this paper two reconfigurable bandpass filters able to switch between WiFi and UMTS for transmit and receive band standards are presented. The filters are designed in such a way that center frequency and bandwidth specifications are precisely met by defining two switchable filter topologies. Design specifications require two center frequency states, one at 2.440 GHz with an 80 MHz bandwidth and a second center frequency state at 1.955 GHz with a 140 MHz bandwidth for the WiFi and UMTS transmit bands. The second filter is able to have one center frequency at 2.440 GHz with an 80 MHz bandwidth and a second center frequency state at 2.165 GHz with a 110 MHz bandwidth for the WiFi and UMTS receive bands, respectively. Filter simulations were performed to match the required filters specifications. Measured results on the transmit filter show a very good agreement with the simulations where a 2.428 GHz center frequency with a 71 MHz bandwidth was obtained for the WiFi state, and a 1.939 GHz center frequency with a 144 MHz bandwidth was obtained for the UMTS filter state. Simulated results on the receive filter show a very good agreement with the specified parameters. The filters specifications were successfully matched with the proposed filter topologies.Postprint (published version

Permittivity and loss characteristics of SU8-quartz composite photoresist at THz frequencies

An SU8-quartz composite photoresist has been fabricated and characterized from 1.2 to 1.4 THz; the material contains quartz particles from 0 to 50 wt%. The composite can reduce the inherent losses of SU8 photoresist at terahertz frequencies. Calculated and measured data is presented and compared with SU8 without quartz inclusions. The results show a reduction in losses and an increase in permittivity in the composite material as the density of quartz particles increases. This initial experiment proves the possibility of modifying the electrical parameters of SU8; increasing the quartz density of the composite will modify these parameters further at THz frequencies.Grant numbers : This work was supported by the Spanish Ministry of Economy and Competitiveness project AETHER (TEC2014-58341-C4-4-R. Part of this work has been supported by the Generalitat de Catalunya under grant 2014SGR 1551

3-D printed band-pass combline filter

This article describes a fourth-order 3-D printed combline filter with a Chebyshev response, operating at central frequency 3 GHz and having a 3% fractional bandwidth. The filter is designed using the coupling matrix theory, fabricated, and experimental results are presented. Comparison between simulations and measurements shows good agreement

Recent advances in reconfigurable microwave filters

In today's communication systems the demand for tunable filters with high performance and with independent control of the filter parameters have been growing. In this paper an overview of several tunable filters that have been proposed over the last years is presented, focused on recent developments involving independent frequency, bandwidth and selectivity control, and high resonator Q filters. � 2011 IEEE

A Discretely Tuned RF-MEMS Bandstop Filter with Wide Tuning Range and Uniform High Rejection

A new bandstop filter is presented providing a two-state discrete wide tuning range from 20 to 30 GHz with the same high rejection level of 36 dB. In the design, metal-insulator-metal capacitors are placed on one end of the resonators and on the other end capacitive micro-electromechanical systems (MEMS) switches are used to discretely tune the centre reject band of the filter

Weighted sum method (a) and reference point method (b) applied to the multi-species management problem using respectively 20 equally distributed pairs of weights and reference points.

<p>Ca is the sum over 20 years of the normalized density of abalone (divided by the maximal density). Cso is the sum over 20 years of the normalized number of sea otters (divided by the maximal number).</p