Recent measurements of compact electronically tunable liquid crystal phase shifter in rectangular waveguide topology

Weickhmann, C.; Nathrath, N.; Gehring, Ralf; Gaebler, Alexander; Jost, Matthias; Jakoby, Rolf

doi:10.1049/el.2013.2281

Cited by 15 publications

(8 citation statements)

References 5 publications

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“…The first experiments in the lab have been carried out with waveguide phase shifters in a split-block design made of brass [68,69]. To assure single-mode propagation in the LC-filled waveguide, smaller dimensions of a = 5.5 mm and b = 2.2 mm are used than those for regular waveguides in this frequency range.…”

Section: Electronic Steerable Horn Antenna Arraymentioning

confidence: 99%

“…To assure single-mode propagation in the LC-filled waveguide, smaller dimensions of a = 5.5 mm and b = 2.2 mm are used than those for regular waveguides in this frequency range. The design and measurement results with LC GT5-26001 over a frequency range from 21 to 35 GHz are given in [68,69]. Over the frequency range from 23 to 27.5 GHz, the matching is better than −12 dB.…”

Section: Electronic Steerable Horn Antenna Arraymentioning

confidence: 99%

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Microwave Liquid Crystal Enabling Technology for Electronically Steerable Antennas in SATCOM and 5G Millimeter-Wave Systems

Jakoby

Gaebler²,

Weickhmann³

2020

Crystals

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Future satellite platforms and 5G millimeter wave systems require Electronically Steerable Antennas (ESAs), which can be enabled by Microwave Liquid Crystal (MLC) technology. This paper reviews some fundamentals and the progress of microwave LCs concerning its performance metric, and it also reviews the MLC technology to deploy phase shifters in different topologies, starting from well-known toward innovative concepts with the newest results. Two of these phase shifter topologies are dedicated for implementation in array antennas: (1) wideband, high-performance metallic waveguide phase shifters to plug into a waveguide horn array for a relay satellite in geostationary orbit to track low Earth orbit satellites with maximum phase change rates of 5.1°/s to 45.4°/s, depending on the applied voltages, and (2) low-profile planar delay-line phase shifter stacks with very thin integrated MLC varactors for fast tuning, which are assembled into a multi-stack, flat-panel, beam-steering phased array, being able to scan the beam from −60° to +60° in about 10 ms. The loaded-line phase shifters have an insertion loss of about 3 dB at 30 GHz for a 400° differential phase shift and a figure-of-merit (FoM) > 120°/dB over a bandwidth of about 2.5 GHz. The critical switch-off response time to change the orientation of the microwave LCs from parallel to perpendicular with respect to the RF field (worst case), which corresponds to the time for 90 to 10% decay in the differential phase shift, is in the range of 30 ms for a LC layer height of about 4 µm. These MLC phase shifter stacks are fabricated in a standard Liquid Crystal Display (LCD) process for manufacturing low-cost large-scale ESAs, featuring single- and multiple-beam steering with very low power consumption, high linearity, and high power-handling capability. With a modular concept and hybrid analog/digital architecture, these smart antennas are flexible in size to meet the specific requirements for operating in satellite ground and user terminals, but also in 5G mm-wave systems.

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Section: Electronic Steerable Horn Antenna Arraymentioning

confidence: 99%

Section: Electronic Steerable Horn Antenna Arraymentioning

confidence: 99%

Microwave Liquid Crystal Enabling Technology for Electronically Steerable Antennas in SATCOM and 5G Millimeter-Wave Systems

Jakoby

Gaebler²,

Weickhmann³

2020

Crystals

View full text Add to dashboard Cite

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“…However, parasitic modes can be excited in this substrate, which degenerate the RF performance. Therefore, stepped-impedance lines are usually used as electrodes to prevent the excitation of these parasitic modes [16,17].…”

Section: Phase Shiftersmentioning

confidence: 99%

Reconfigurable Millimeter-Wave Components Based on Liquid Crystal Technology for Smart Applications

et al. 2020

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This paper presents recent development of tunable microwave liquid crystal (LC) components in the lower millimeter wave (mmW) regime up to the W-band. With the utilization of increasing frequency, conventional metallic waveguide structures prove to be impractical for LC-based components. In particular, the integration of the electric bias network is extremely challenging. Therefore, dielectric waveguides are a promising alternative to conventional waveguides, since electrodes can be easily integrated in the open structure of dielectric waveguides. The numerous subcategories of dielectric waveguides offer a high degree of freedom in designing smart millimeter wave components such as tunable phase shifters, filters and steerable antennas. Recent research resulted in many different realizations, which are analyzed in this paper. The first demonstrators of phased array antennas with integrated LC-based phase shifters are reviewed and compared. In addition, beam steering with a single antenna type is shown. Furthermore, the possibility to realize tunable filters using LC-filled dielectric waveguides is demonstrated.

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“…A literature search produces some instances of LC based phased array antennas [14][15][16][17]. These studied devices typically use a standard nematic liquid crystal as the tuning medium.…”

Section: Introductionmentioning

confidence: 99%

Eight-element liquid crystal based 32 GHz phased array antenna with improved time response

et al. 2021

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Phased array radar systems are used for a wide variety of applications including the precise tracking of airborne craft for air traffic control and providing accurate atmospheric condition information important in weather forecasting. Reducing the cost and size of these radar systems will open new fields to the use of this technology. Using phase control implemented through liquid crystal materials we have created a compact, phased array radar system operating in the microwave range. We report on the construction and testing of a linear, eight element phased array antenna system operating at 32 GHz with element phase controlled by a dual frequency nematic liquid crystal media used as a tunable dielectric. The system was designed using CST Design Studios and Ansys HFSS software. Dual frequency liquid crystals are used to improve beam steering response times. We demonstrate 42 millisecond beam switching times, defined as the time to change the beam focus from one point to another point, controllable beam formation, and beam steering profiles consistent with analytical results and simulation models. The device footprint is a square with sides 9.5 cm long and a thickness less than 2.5 mm. Such a module is easily stackable to create an 8 × 8 phased array system. Our design incorporates a modular construction using PCB for the antennas and input circuitry and a liquid crystal phase control cell with microwave glass substrates. This design simplifies design, construction, and testing as compared to on-glass designs. The device shows an improvement in point-to-point scanning speeds by a factor of 3 as compared to similar liquid crystal based devices and provides continuously variable tuning. Such a device can be used in a system for reduced visibility, directional range finding suitable for automobile collision avoidance systems and rotary wing aircraft landing aids.

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Recent measurements of compact electronically tunable liquid crystal phase shifter in rectangular waveguide topology

Cited by 15 publications

References 5 publications

Microwave Liquid Crystal Enabling Technology for Electronically Steerable Antennas in SATCOM and 5G Millimeter-Wave Systems

Microwave Liquid Crystal Enabling Technology for Electronically Steerable Antennas in SATCOM and 5G Millimeter-Wave Systems

Reconfigurable Millimeter-Wave Components Based on Liquid Crystal Technology for Smart Applications

Eight-element liquid crystal based 32 GHz phased array antenna with improved time response

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