Microwave Tunable Notch Filter Based on Liquid Crystal Using Spiral Spurline Technology

Torrecilla, Javier; Ávila-Navarro, Ernesto; Marcos, Carlos; Urruchi, V.; Sánchez‐Pena, José Manuel; Arias,; Sánchez-López, Marı́a del Mar

doi:10.1002/mop.27812

Cited by 15 publications

(16 citation statements)

References 15 publications

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“…For a fixed stub length 1 , can be adjusted by tuning the effective permittivity of the LC material using a biased voltage. Figure 3(b) is a conventional spurline structure, which has been used to realize LC based BSFs recently [20,21]. With the same substrate and dimensions for the structures in Figure 3(c), where we can see that the stub structure of Figure 3(a) has a wider stopband bandwidth and a larger attenuation at the rejection frequency.…”

Section: Wave Interference Techniques and Design Of The Band-stopmentioning

confidence: 97%

Compact Liquid Crystal Based Tunable Band-Stop Filter with an Ultra-Wide Stopband by Using Wave Interference Technique

Cai

Chu

2017

International Journal of Antennas and Propagation

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A wave interference filtering section that consists of three stubs of different lengths, each with an individual stopband of its own central frequency, is reported here for the design of band-stop filters (BSFs) with ultra-wide and sharp stopbands as well as large attenuation characteristics. The superposition of the individual stopbands provides the coverage over an ultra-wide frequency range. Equations and guidelines are presented for the application of a new wave interference technique to adjust the rejection level and width of its stopband. Based on that, an electrically tunable ultra-wide stopband BSF using a liquid crystal (LC) material for ultra-wideband (UWB) applications is designed. Careful treatment of the bent stubs, including impedance matching of the main microstrip line and bent stubs together with that of the SMA connectors and impedance adaptors, was carried out for the compactness and minimum insertion and reflection losses. The experimental results of the fabricated device agree very well with that of the simulation. The centre rejection frequency as measured can be tuned between 4.434 and 4.814 GHz when a biased voltage of 0–20 Vrms is used. The 3 dB and 25 dB stopband bandwidths were 4.86 GHz and 2.51 GHz, respectively, which are larger than that of other recently reported LC based tunable BSFs.

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Section: Wave Interference Techniques and Design Of The Band-stopmentioning

confidence: 97%

Compact Liquid Crystal Based Tunable Band-Stop Filter with an Ultra-Wide Stopband by Using Wave Interference Technique

Cai

Chu

2017

International Journal of Antennas and Propagation

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“…2) which has already been reported in previous works [10]. A Taconic TLX−08 (e r = 2.38), 0.25 mm−thick dielectric layer is used to define the LC cavity and to separate the upper from the lower substrate.…”

Section: Device Manufacturingmentioning

confidence: 89%

Liquid crystal dual-mode band-pass filter with improved performance

Torrecilla

Marcos

Urruchi

et al. 2015

Opto-Electronics Review

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Over the last twenty years, there has been a growing interest in the design of tunable devices at microwave frequencies by us- ing liquid crystals technology. In particular, the use of liquid crystals with high dielectric anisotropy allows manufacturing voltage-controlled devices to operate in a wide frequency range. In this work the frequency response of a liquid crystal band-pass filter with dual-mode microstrip structure has been studied in depth by using a simulation software tool. A reshap- ing of a conventional dual-mode square patch resonator bandpass filter with a square notch, studied in the literature, has been proposed with the goal of improving the filter performance. The main features achieved are a significant increase in the return loss of the filter and a narrowing of a 3-dB bandwidth. Specifically, a reduction in the filter bandwidth from 800 MHz to 600 MHz, which leads to a return loss increase from 6 dB to 12.5 dB, has been achieved. The filter centre frequency can be tuned from 4.54 GHz to 5.19 GHz.

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“…For this reason, the filter is implemented by using an inverted-microstrip structure, as shown in Figure 2. This structure has been already reported in other LC-based devices [12]. The LC cavity is designed of 0.25-mm thick and delimited by the spacers; the dielectric material Taconic TLX-08 (ε r = 2.55) is employed for them.…”

Section: Liquid Crystal Bandpass Filter Designmentioning

confidence: 99%

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

et al. 2014

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In this paper, the design and experimental characterization of a tunable microstrip bandpass filter based on liquid crystal technology are presented. A reshaped microstrip dual-mode filter structure has been used in order to improve the device performance. Specifically, the aim is to increase the pass-band return loss of the filter by narrowing the filter bandwidth. Simulations confirm the improvement of using this new structure, achieving a pass-band return loss increase of 1.5 dB at least. Because of the anisotropic properties of LC molecules, a filter central frequency shift from 4.688 GHz to 5.045 GHz, which means a relative tuning range of 7.3%, is measured when an external AC voltage from 0 Vrms to 15 Vrms is applied to the device.

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Microwave Tunable Notch Filter Based on Liquid Crystal Using Spiral Spurline Technology

Cited by 15 publications

References 15 publications

Compact Liquid Crystal Based Tunable Band-Stop Filter with an Ultra-Wide Stopband by Using Wave Interference Technique

Compact Liquid Crystal Based Tunable Band-Stop Filter with an Ultra-Wide Stopband by Using Wave Interference Technique

Liquid crystal dual-mode band-pass filter with improved performance

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

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