Liquid Crystal-Reconfigurable Antenna Concepts for Space Applications at Microwave and Millimeter Waves

Gaebler, Alexander; Moessinger, Alexander; Goelden, F.; Manabe, Atsutaka; Goebel, M.; Follmann, Rüdiger; Koether, D.; Modes, Christina; Kipka, Annette; Deckelmann, M.; Rabe, Torsten; Schulz, B.; Kuchenbecker, Petra; Lapanik, A.; Mueller, Stefan; Haase, Wolfgang; Jakoby, Rolf

doi:10.1155/2009/876989

Cited by 59 publications

(29 citation statements)

References 9 publications

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“…Instead, some LC mixtures have been reported in literature to be stable in the exposure of protons. 9 Additional favorable features, such as low power consumption and no moving mechanical parts suggest LCs as candidates in these applications. In contrast, insertion losses of LC devices are a key parameter concerning to the device performance not so promising for microwave applications and clear efforts should be focused on further reduction of this feature.…”

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confidence: 99%

Note: Tunable notch filter based on liquid crystal technology for microwave applications

Urruchi

Marcos

Torrecilla

et al. 2013

Review of Scientific Instruments

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In this work, a compact design of an electrically tunable notch filter, based on liquid crystal (LC) technology, has been designed, manufactured, and characterized. The proposal has been achieved through particular configuration schemes with low cost inverted-microstrip structures and conventional spurlines structures due to its ease of integration. Central frequency tunability has been induced by applying low ac voltages, thus involving low power consumption. For these devices, filter responses have been approached specifically at microwave C-band frequency allocated for many satellite communications applications. Also, it has taken advantage of new highly anisotropic nematic LC mixtures at those frequency ranges. Recently, liquid crystal (LC) technology has begun to be used in nonoptical applications due to its promising features in further electronic applications ranging from kilohertz to megahertz frequencies. Intrinsic anisotropy of some LC properties, which implies different properties depending of the direction in which they are measured, allows new advanced devices to be designed with tunable features, by using these materials.The use of LC to design tunable devices at microwave frequency bands is not a new conception; nevertheless there has been an increasing interest in improving their performance, particularly in the last decade. Liquid crystals were recognized as candidates for microwave dielectric substrates in the early 1990s. 1 Although first approaches to LC devices in waveguides led to bulky and large consumption designs (due to strong magnetic fields for switching LC molecules), most of the recent prototypes, such as tunable phase shifters, 2, 3 capacitors, 4 filters, 5,6 or antennas, 7 have reported practical functions involving electric fields for orienting LC at those frequencies.Filters are very valuable devices because they represent a powerful tool for frequency response processing. They are designed in order to select or to remove bands of frequency. A band-rejection filter or band-stop filter is a filter that attenuates a frequency band, while the other frequencies remain unchanged. A notch filter is a band-rejection filter with a narrow stopband, with a high quality factor, that is mainly used to remove spurious frequencies and to filter noise signals.In this work, the design of a notch filter for about 5 GHz rejection frequency (f 0 ), based on the electric field switching of a LC, has been proposed and its feasibility has been demonstrated. Filters working at this frequency, allocated in the C-band, are intended to be used in satellite telecommunication systems or, for example, to avoid the interference a) Author to whom correspondence should be addressed. Electronic mail:vurruchi@ing.uc3m.es.between the UWB (Ultra Wide-Band) and WLAN (Wireless Local Area Networks) systems. 8 UWB systems are particularly promising for short-range high-throughput wireless communications. Multiple solutions have been proposed for providing tunability in microwave devices, such as varactors based on sem...

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confidence: 99%

Note: Tunable notch filter based on liquid crystal technology for microwave applications

Urruchi

Marcos

Torrecilla

et al. 2013

Review of Scientific Instruments

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“…In a research project named "Liquida" industry companies, research companies and university institutes (see e.g. [2]) are working to overcome that problem with the aim to develop tuneable components for RF applications. The combination of both , good RF properties of LC and the advantage of the standard multiplayer technology of Low Temperature Co-fired Ceramics (LTCC) have a high potential to enable the realization of cost effective and high performance RF components.…”

Section: Integrated Phased Array Antennas With Liquid Crystal Phasmentioning

confidence: 99%

“…They have a relative permittivity perpendicular to an incident static electrical field r, ε ⊥ which is usually around 2.5 while r, ε , the relative dielectric constant parallel to a static electrical field, is in the order of 2.8. An LC mixture BMW 10, developed at the Technical University Darmstadt for maximum optical anisotropy, but featuring also acceptable microwave performance, yielded GHz [2]. If the static electrical field is directed between the two positions parallel and perpendicularly to the crystal axes, the relative dielectric constant can be continuously varied between the two extreme values.…”

Section: Integrated Phased Array Antennas With Liquid Crystal Phasmentioning

confidence: 99%

Integrated beam steerable antennas in LTCC-technology

Wolff

2010

2010 International Workshop on Antenna Technology (iWAT)

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Two concepts of building highly integrated beam steerable antennas for space applications are described: As a first example an integrated phased array antenna using liquid crystal phase shifters in a LTCC technology shows promising results for application in space communication. As a second example a fully integrated digital beam steering antenna in LTCC technology demonstrates how a high integration factor for a very complex antenna system including active microwave circuits and a cooling system can be realized.

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“…One example are microwaves devices, a recent and very active research field focused on building antennas, phase shifters or filters based on liquid crystals [1]. How− ever, on the other hand, photonic applications based on these materials have already been extensively researched; covering many diverse fields.…”

Section: Introductionmentioning

confidence: 99%