Investigation of Planar Transmission Lines on Liquid Crystal Substrates at mm-Wave Frequencies

毫米波频率液晶基板上平面传输线的研究

• 批准号: EP/E056695/1
• 负责人: Dariush Mirshekar
• 金额: $ 55.96万
• 依托单位: University of Essex
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2007
• 资助国家: 英国
• 起止时间: 2007 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FE056695%2F1
• 关键词: Investigation; Planar; Transmission; Lines; Liquid

Mobile and wireless communication systems as well as radar systems require reconfigurable filters, tuneable and adaptive antennas, adaptive couplers, electronically controlled delay-lines, etc, in order to be flexible and operational under different communication standards. Also, for security reasons, lightweight field radios and radar systems are required to reconfigure and operate over different frequency bands in a short time span. Some earlier research have shown that liquid crystals would be particularly attractive for these applications. Liquid crystals offer the possibility of large permittivity changes, controlled by low, externally applied voltages, so their incorporation as substrates in microwave devices can bring about many advantages into communication and radar devices and revolutionise adaptive/reconfigurable systems. It is necessary to explore the possibilities offered by liquid crystals thoroughly, with a full characterisation of the materials at the frequencies and geometries involved. It is also important to develop accurate modelling techniques that can predict the behaviour of liquid crystal materials in complex device configurations and can then take into account the anisotropy and non-uniformity of its permittivity distribution in the modelling of the RF operation of the device. The liquid crystal properties can be controlled by changing the components in the mixtures, but in order to formulate the mixtures the properties must be measured over the relevant frequency ranges. In this work we will develop methods and measure dielectric constants, losses, natural resonances, nonlinearities of RF liquid crystals and we will obtain theoretically and experimentally similar parameters for liquid crystal based microstrip and coplanar waveguide from 30 GHz to 110 GHz. Modelling of the liquid crystal behaviour and of the wave propagation in simple devices will be used alongside experimental measurements to design, fabricate and test prototypes of practical devices including two reconfigurable filters.

移动的和无线通信系统以及雷达系统需要可重新配置的滤波器、可调谐和自适应天线、自适应耦合器、电子控制的延迟线等，以便在不同的通信标准下是灵活的和可操作的。此外，出于安全原因，要求轻型野外无线电和雷达系统在短时间内重新配置并在不同频带上运行。一些早期的研究表明，液晶对于这些应用特别有吸引力。液晶提供了大的介电常数变化的可能性，由低的外部施加的电压控制，因此它们作为微波器件中的衬底的结合可以为通信和雷达器件带来许多优点，并彻底改变自适应/可重构系统。有必要彻底探索液晶提供的可能性，并在所涉及的频率和几何形状下对材料进行全面表征。同样重要的是开发精确的建模技术，该技术可以预测复杂器件配置中液晶材料的行为，并且然后可以在器件的RF操作的建模中考虑其介电常数分布的各向异性和非均匀性。液晶性质可以通过改变混合物中的组分来控制，但是为了配制混合物，必须在相关频率范围内测量性质。在这项工作中，我们将开发的方法和测量的介电常数，损耗，自然谐振，RF液晶的非线性，我们将获得理论和实验上类似的参数，液晶微带和共面波导从30 GHz到110 GHz。液晶行为和简单设备中的波传播的建模将与实验测量一起使用，以设计，制造和测试包括两个可重构滤波器的实际设备的原型。

项目成果

Meander line millimetre-wave liquid crystal based phase shifter

• DOI: 10.1049/el.2010.3513
• 发表时间: 2010-05
• 期刊: Electronics Letters
• 影响因子: 1.1
• 作者: S. Bulja;D. Mirshekar-Syahkal

60 GHz Reflection Type Phase Shifter based on liquid crystal

基于液晶的60 GHz反射型移相器

• DOI: 10.1109/rws.2010.5434253
• 发表时间: 2010
• 作者: Bulja S

Accurate Modeling for Wideband Characterization of Nematic Liquid Crystals for Microwave Applications

• DOI: 10.1109/tmtt.2009.2033864
• 发表时间: 2009-12-01
• 期刊: IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES
• 影响因子: 4.3
• 作者: James, Richard;Fernandez, F. Anibal;Mirshekar-Syahkal, Dariush
• 通讯作者: Mirshekar-Syahkal, Dariush

Planar transmission line method for measurement of dielectric constants of liquid crystals in 60 GHz band

60 GHz 频段液晶介电常数测量的平面传输线法

• DOI: 10.1109/apmc.2009.5385377
• 发表时间: 2009
• 作者: Bulja S

Liquid-crystal-based mm-wave tunable resonator

• 发表时间: 2010-11
• 期刊: The 40th European Microwave Conference
• 作者: M. Yazdanpanahi;S. Bulja;D. Mirshekar-Syahkal;R. James;S. Day;F. Fernández