scholarly journals Potential of Liquid-Crystal Materials for Millimeter-Wave Application

2018 ◽  
Vol 8 (12) ◽  
pp. 2544 ◽  
Author(s):  
Toshiaki Nose ◽  
Ryota Ito ◽  
Michinori Honma
Keyword(s):  
Liquid Crystal ◽  
Millimeter Wave ◽  
Microstrip Line ◽  
Phase Shifter ◽  
Substrate Surface ◽  
Antenna System ◽  
Phase Shifters ◽  
Phased Array Antenna ◽  
Electric Circuits ◽  
Line Type

In this study, we reviewed three topics regarding the application of liquid-crystal (LC) materials to millimeter-wave (MMW) devices. It is essential to develop useful measurement methods for refractive indices of LC materials in the MMW region. Herein, a novel measurement method using optical short is demonstrated using a Si semiconductor substrate. There are two approaches to develop MMW LC devices. One is the quasi-optical approach, which involves scaling up the optical components, and the other approach involves integrating the LC materials into high-frequency electric circuits. A three-dimensional (3D) printer is used to fabricate the Fresnel lens, which is a typical quasi-optical device useful in the MMW region, where we can develop the tunable lens by introducing LC materials. A planar-type MMW waveguide is advantageous for integrating the LC materials to develop LC MMW devices using the second approach. We investigated a useful microstrip-line-type LC phase shifter by developing a novel conversion circuit to introduce the LC material onto the dielectric substrate surface. A phase shifter is an important MMW component that is used to attain a phased array antenna system, and a minimal twin antenna array is demonstrated using the microstrip-line-type LC phase shifters.

Improved High-Frequency Performance of Microstrip-Line-Type Liquid Crystal Phase Shifter

2013 ◽  
Vol 52 (9R) ◽  
pp. 091701 ◽  
Author(s):  
Toshiaki Nose ◽  
Liang-Chy Chien ◽  
Otilia Catanescu ◽  
Andrii Golvin ◽  
Yusuke Ito ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
High Frequency ◽  
Microstrip Line ◽  
Phase Shifter ◽  
Crystal Phase ◽  
Liquid Crystal Phase ◽  
Line Type ◽  
High Frequency Performance

Fundamental Properties of Novel Design Microstrip Line Type of Liquid Crystal Phase Shifter in Microwave Region

2012 ◽  
Vol 51 (4R) ◽  
pp. 044104 ◽  
Author(s):  
Ryouta Ito ◽  
Takayuki Kawakami ◽  
Yusuke Ito ◽  
Takayuki Sasamori ◽  
Yoji Isota ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Microstrip Line ◽  
Phase Shifter ◽  
Crystal Phase ◽  
Liquid Crystal Phase ◽  
Microwave Region ◽  
Fundamental Properties ◽  
Novel Design ◽  
Line Type

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

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 514 ◽  
Author(s):  
Rolf Jakoby ◽  
Alexander Gaebler ◽  
Christian Weickhmann
Keyword(s):  
Liquid Crystal ◽  
Phase Shift ◽  
Millimeter Wave ◽  
Phase Shifter ◽  
Beam Steering ◽  
Phase Shifters ◽  
Worst Case ◽  
Differential Phase Shift ◽  
Digital Architecture ◽  
Differential Phase

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.

Fundamental Properties of Novel Design Microstrip Line Type of Liquid Crystal Phase Shifter in Microwave Region

2012 ◽  
Vol 51 ◽  
pp. 044104 ◽  
Author(s):  
Ryouta Ito ◽  
Takayuki Kawakami ◽  
Yusuke Ito ◽  
Takayuki Sasamori ◽  
Yoji Isota ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Microstrip Line ◽  
Phase Shifter ◽  
Crystal Phase ◽  
Liquid Crystal Phase ◽  
Microwave Region ◽  
Fundamental Properties ◽  
Novel Design ◽  
Line Type

Reliability study of a tunable Ka-band SIW-phase shifter based on liquid crystal in LTCC-technology

2014 ◽  
Vol 7 (5) ◽  
pp. 521-527 ◽  
Author(s):  
Sebastian Strunck ◽  
Alexander Gaebler ◽  
Onur H. Karabey ◽  
Andreas Heunisch ◽  
Baerbel Schulz ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Phase Shifter ◽  
Effective Permittivity ◽  
Phase Shifters ◽  
Phased Array Antenna ◽  
Differential Phase Shift ◽  
Differential Phase ◽  
Phase Errors ◽  
Antenna Module ◽  
High Level

A tunable substrate-integrated waveguide phase shifter using low-temperature co-fired ceramic (LTCC)-technology is presented in this paper. By changing the effective permittivity in the liquid crystal (LC)-filled waveguide, the differential phase can be tuned continuously. This is achieved by means of an analog signal applied to the electrodes, surrounding the LC. The design allows for precise tuning of the differential phase, which is proven with a Monte Carlo measurement resulting in phase errors of less than 3° at 28 GHz. Besides that, the ambient temperature dependency of the module is shown. The phase shifter has a high integration level and can be included into a complete and lightweight single-phased array antenna module. The phase shifter is realized with a high level of integration which is available through the multilayer process of the LTCC. It has a length of 50 and provides a differential phase shift of more than 360° at 28 GHz. The figure of merit for tunable phase shifters is >40°/dB.

Analysis of Optimum Precoding schemes in Millimeter Wave System

2020 ◽  
Vol 13 ◽  
Author(s):  
Divya Singh ◽  
Aasheesh Shukla
Keyword(s):  
Power Consumption ◽  
Millimeter Wave ◽  
Spectral Efficiency ◽  
Phase Shifter ◽  
Phase Shifters ◽  
Achievable Rate ◽  
Wave System ◽  
Digital To Analog Converter ◽  
Hybrid Precoding ◽  
Analog Converter

Background : Millimeter wave technology is the emerging technology in wireless communication due to increased demand for data traffic and its numerous advantages however it suffers from severe attenuation. To mitigate this attenuation, phased antenna arrays are used for unidirectional power distribution. An initial access is needed to make a connection between the base station and users in millimeter wave system. The high complexity and cost can be mitigated by the use of hybrid precoding schemes. Hybrid precoding techniques are developed to reduce the complexity, power consumption and cost by using phase shifters in place of converters. The use of phase shifters also increases the spectral efficiency. Objective: Analysis of Optimum Precoding schemes in Millimeter Wave System. Method: In this paper, the suitability of existing hybrid precoding solutions are explored on the basis of the different algorithms and the architecture to increase the average achievable rate. Previous work done in hybrid precoding is also compared on the basis of the resolution of the phase shifter and digital to analog converter. Results: A comparison of the previous work is done on the basis of different parameters like the resolution of phase shifters, digital to analog converter, amount of power consumption and spectral efficiency. Table 2 shows the average achievable rate of different algorithms at SNR= 0 dB and 5 dB. Table 3 also compares the performance achieved by the hybrid precoder in the fully connected structure with two existing approaches, dynamic subarray structure with and without switch and sub connected or partially connected structure. Table 4 gives the comparative analysis of hybrid precoding with the different resolutions of the phase shifter and DAC. Conclusion: In this paper, some available literature is reviewed and summarized about hybrid precoding in millimeter wave communication. Current solutions of hybrid precoding are also reviewed and compared in terms of their efficiency, power consumption, and effectiveness. The limitations of the existing hybrid precoding algorithms are the selection of group and resolution of phase shifters. The mm wave massive MIMO is only feasible due to hybrid precoding.

scholarly journals Temperature Characterization of Liquid Crystal Dielectric Image Line Phase Shifter for Millimeter-Wave Applications

Crystals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 63
Author(s):  
Henning Tesmer ◽  
Rani Razzouk ◽  
Ersin Polat ◽  
Dongwei Wang ◽  
Rolf Jakoby ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Millimeter Wave ◽  
Insertion Loss ◽  
Phase Shifter ◽  
Ground Plane ◽  
Temperature Dependent ◽  
Differential Phase ◽  
Dependent Behavior ◽  
The Impact ◽  
Temperature Dependent Behavior

In this paper we investigate the temperature dependent behavior of a liquid crystal (LC) loaded tunable dielectric image guide (DIG) phase shifter at millimeter-wave frequencies from 80 GHz to 110 GHz for future high data rate communications. The adhesive, necessary for precise fabrication, is analyzed before temperature dependent behavior of the component is shown, using the nematic LC-mixture GT7-29001. The temperature characterization is conducted by changing the temperature of the LC DIG’s ground plane between −10∘C and 80 ∘C. The orientation of the LC molecules, and therefore the effective macroscopic relative permittivity of the DIG, is changed by inserting the temperature setup in a fixture with rotatable magnets. Temperature independent matching can be observed, while the insertion loss gradually increases with temperature for both highest and lowest permittivity of the LC. At 80 ∘C the insertion loss is up to 1.3dB higher and at −10∘C it is 0.6dB lower than the insertion loss present at 20 ∘C. In addition, the achievable differential phase is reduced with increasing temperature. The impact of molecule alignment to this reduction is shown for the phase shifter and an estimated 85% of the anisotropy is still usable with an LC DIG phase shifter when increasing the temperature from 20 ∘C to 80 ∘C. Higher reduction of differential phase is present at higher frequencies as the electrical length of the phase shifter increases. A maximum difference in differential phase of 72∘ is present at 110 GHz, when increasing the temperature from 20 ∘C to 80 ∘C. Nevertheless, a well predictable, quasi-linear behavior can be observed at the covered temperature range, highlighting the potential of LC-based dielectric components at millimeter wave frequencies.

scholarly journals Memristors as Candidates for Replacing Digital Potentiometers in Electric Circuits

Electronics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 181
Author(s):  
Ivo Marković ◽  
Milka Potrebić ◽  
Dejan Tošić
Keyword(s):  
Phase Shifter ◽  
Voltage Divider ◽  
Frequency Characteristics ◽  
Phase Shifters ◽  
Pass Filter ◽  
Electric Circuits ◽  
Digital Potentiometer ◽  
Memristive Circuits ◽  
Parasitic Effects ◽  
Additional Level

Digital potentiometers are substantial components for the design of many mixed-signal electronic circuits and systems. Their capability to program resistance value almost instantly provides hardware designers an additional level of freedom. Unfortunately, this feature is limited to DC and lower frequencies, due to parasitic effects. Nowadays, memristors as continuously tunable resistors are becoming candidates for potentiometer successors. Memristors are two-terminal non-volatile devices which have less significant parasitic effects and a wide resistance range. The memristance value can be changed on the fly. Using nanotechnology, memristor implementation has a nanoscale footprint with nanosecond transition between resistive states. In this paper, we present a comparison between the frequency characteristics of digital potentiometers and the only commercially available memristors. Memristor parasitic effects dominate at higher frequencies which extends the bandwidth. In order to present the advantages of memristive circuits, we have analyzed and implemented tunable circuits such as a voltage divider, an inverting amplifier, a high-pass filter, and a phase shifter. A commercially available memristor by KnowM Inc. is used for this purpose. Experimental results obtained by the measurements verify that a memristor has equal or better characteristics than a digital potentiometer. Memristive realizations of voltage dividers and inverting amplifiers have a wider bandwidth, while filters and phase shifters with a memristor have almost identical frequency characteristics as the corresponding realizations with a digital potentiometer.

Phased-array antennas using novel PSoC-controlled phase shifters for wireless applications

2021 ◽  
pp. 1-13
Author(s):  
Aparna B. Barbadekar ◽  
Pradeep M. Patil
Keyword(s):  
Insertion Loss ◽  
Phase Shifter ◽  
Phased Array ◽  
Phase Shifters ◽  
Control Circuit ◽  
Power Divider ◽  
Phased Array Antenna ◽  
Phased Array Antennas ◽  
Array Antennas ◽  
Low Insertion Loss

Abstract The paper proposes a system consisting of novel programmable system on chip (PSoC)-controlled phase shifters which in turn guides the beam of an antenna array attached to it. Four antennae forming an array receive individual inputs from the programmable phase shifters (IC 2484). The input to the PSoC-based phase shifter is provided from an optimized 1:4 Wilkinson power divider. The antenna consists of an inverted L-shaped dipole on the front and two mirrored inverted L-shaped dipoles mounted on a rectangular conductive structure on the back which resonates in the ISM/Wi-Fi band (2.40–2.48 GHz). The power divider is designed to provide the feed to the phase shifter using a beamforming network while ensuring good isolation among the ports. The power divider has measured S11, S21, S31, S41, and S51 to be −14, −6.25, −6.31, −6.28, and −6.31 dB, respectively at a frequency of 2.45 GHz. The ingenious controller is designed in-house using a PSoC microcontroller to regulate the control voltage of individual phase shifter IC and generate progressive phase shifts. To validate the calibration of the in-house designed control circuit, the phased array is simulated using $s_p^2$ touchstone file of IC 2484. This designed control circuit exhibits low insertion loss close to −8.5 dB, voltage standing wave ratio of 1.58:1, and reflection coefficient (S11) is −14.36 dB at 2.45 GHz. Low insertion loss variations confirm that the phased-array antenna gives equal amplitude and phase. The beamforming radiation patterns for different scan angles (30, 60, and 90°) for experimental and simulated phased-array antenna are matched accurately showing the accuracy of the control circuit designed. The average experimental and simulated gain is 13.03 and 13.48 dBi respectively. The in-house designed controller overcomes the primary limitations associated with the present electromechanical phased array such as cost weight, size, power consumption, and complexity in design which limits the use of a phased array to military applications only. The current study with novel design and enhanced performance makes the system worthy of the practical use of phased-array antennas for common society at large.

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