Improving the Pass-Band Return Loss in Liquid Crystal  Dual-Mode Bandpass Filters by Microstrip Patch Reshaping

Torrecilla, Javier; Urruchi, V.; Sánchez‐Pena, José Manuel; Bennis, N.; García, Alejandro; Segovia, D.

doi:10.3390/ma7064524

Cited by 6 publications

(4 citation statements)

References 11 publications

(9 reference statements)

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“…A constant volume of a single liquid of varying permittivity can be used. These liquid crystals have been used in microwave applications such as: Tunable band-pass filters [14][15][16][17], Tunable band-stop/notch filters [18][19][20], reconfigurable reflectarray [21,22]. Nevertheless, the tuning potential of such systems essentially depends on the permittivity range achievable by the liquid crystals used.…”

Section: Introductionmentioning

confidence: 99%

RF MEMS filter based on dual liquid variations

Habbachi¹,

Besbes²

2022

J. Micromech. Microeng.

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This paper discusses the behavior of RF MEMS tunable microwave filter. We have modeled the distribution of magnetic field and electric current density in order to reveal the comportment of each device and to evaluate the relation between the frequency response and the microwave performances. From several modelling and simulations, we catch the resonance phenomenon for magnetic and electric fields at different conditions. Hence, in order to develop a reconfigurable MEMS ensuring a function of tunable band-pass filters, we have identified conditions allowing to vary the resonance frequency from Fres = 0.42 GHz to Fres = 1.85 GHz ensuring a large total variation of Tr = 340.5%. The structure is fabricated using SU-8 resin for circulating microchannels and sealing layers. The extracted parameters from measurements results and retro-simulation reveal a diminution of the total tuning range.

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Section: Introductionmentioning

confidence: 99%

RF MEMS filter based on dual liquid variations

Habbachi¹,

Besbes²

2022

J. Micromech. Microeng.

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“…In [24], the series-fed patch array is used to design antennas; it can change the operating frequency from 14.5 to 16.4GHz. In [27] and [28], two types of tunable filters based on a dual mode structure and DBR topology are reported, and they achieve a tunability of 6% at 5GHz…”

Section: Introductionmentioning

confidence: 99%

“…and 6% at 4GHz, respectively. However, in simulating these tunable devices, such as in [24,27,28], the LC is treated as an isotropic material, ignoring the LC anisotropy. It can be seen from much of the previous work that there is a lack of a general design method for microstrip tunable devices based on LC technology.…”

Section: Introductionmentioning

confidence: 99%

A general design method for tunable microstrip devices at microwave frequency based on liquid crystal technology

et al. 2019

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This work was supported in part by the EPSRC under grant [EP/I003894/1]. A general design method for tunable microstrip devices at microwave frequency based on liquid crystal technology This paper proposes a general design method for microstrip devices using liquid crystals (LCs) at microwave frequency. The method employs lumped element modelling to first optimise the filter at the working frequency. Then EM simulation is used for the second optimisation and the full-wave simulation. LC is used as the tunable material since the anisotropy can be changed with low voltages. The approach of modelling of LC as a homogeneous anisotropy demonstrated with Computer Simulation Technology (CST) Microwave Studio is an acceptable approximation, which accurately predicts the tuning range. A new tunable inverted microstrip filter using nematic LCs at millimetre-wave frequencies is designed to verify the method. The proposed design utilises interdigital capacitors in parallel with two inductive loops to form a bandpass filter. It is fabricated and measured, and shows that the centre frequency varies from 5.01 to 5.51GHz (10% tunability) and achieves a 3-dB bandwidth of 450MHz, which is in good agreement with simulation results. A finite-element simulation is used to investigate the detailed behaviour of LC directors in the fully switched state; the effective permittivity is extracted from the finite-element simulation and used in CST to achieve an even more accurate agreement with experimental results.

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“…In many emerging multiband communication systems, microwave frequency-tunable filters are required with advanced features in terms of functionality and reduced volume and complexity [ 1 , 2 ]. Thus, several strategies using, for example, micro-electromechanical systems, ferroelectrics, liquid crystal, and magnetic materials, or varactor diode-based technologies have been used to reach these requirements [ 3 , 4 , 5 , 6 , 7 , 8 , 9 ]. MEMS switches present high quality factor.…”

Section: Introductionmentioning

confidence: 99%

Reconfigurable Coplanar Waveguide (CPW) and Half-Mode Substrate Integrated Waveguide (HMSIW) Band-Stop Filters Using a Varactor-Loaded Metamaterial-Inspired Open Resonator

et al. 2017

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An open ring resonator (ORR) loaded with a varactor diode is designed and implemented in order to achieve high-performance tunable band-stop filters in planar technology with a compact size. This varactor-loaded ORR (VLORR) is versatile. It allows a shunt connection with different planar waveguide sections. In this paper, it has been connected to a coplanar waveguide (CPW) and a half-mode substrate integrated waveguide (HMSIW). As a reverse bias voltage is applied to the VLORR, a continuous tuning over the resulting stop-band can be achieved. To illustrate the possibilities of the VLORR, three prototypes have been designed, fabricated, and characterized. The three prototypes show an outstanding performance, with a rejection level at the resonant frequency and a tuning range greater than 12 dB and 85%, respectively. This VLORR has high potential value in microwave communication systems to eliminate unwanted signals.

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Improving the Pass-Band Return Loss in Liquid Crystal Dual-Mode Bandpass Filters by Microstrip Patch Reshaping

Cited by 6 publications

References 11 publications

RF MEMS filter based on dual liquid variations

RF MEMS filter based on dual liquid variations

A general design method for tunable microstrip devices at microwave frequency based on liquid crystal technology

Reconfigurable Coplanar Waveguide (CPW) and Half-Mode Substrate Integrated Waveguide (HMSIW) Band-Stop Filters Using a Varactor-Loaded Metamaterial-Inspired Open Resonator

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