Variable Dielectric Delay Lines in Liquid Crystals for Phased Array Feeds

在这个项目中，我们寻求开发一种新的液晶技术，这种技术可以将可控的真实时间延迟应用于频率高达数十千兆赫的射频信号。该基础技术已得到验证，并具有广泛的应用前景。我们现在打算利用这项技术来构建一个真正的延迟线天文演示系统，并展示这些系统可以集成到现有相控阵馈电(PAF)仪器的波束形成模块中，从而极大地提高其能力。PAF是射电天文学必不可少的下一步。它们提供了增加望远镜视场(FOV)的可能性，改进了校准，并允许操作到更高的频率。PAF已经在PHAROS等仪器中实现，可以实现这些目标，但由于波束形成器硬件中使用移相器，因此带宽很窄。在这个项目中，我们试图实现一个真正的时延波束形成器，它将允许所有可用的带宽被使用。这将利用新技术-液晶带状线，其介电常数可以通过施加交流电压来改变。我们提出了一个为期两年的计划，在此期间，我们将使用一组实时延迟单元来生产PAF模块，并在Pharos接收器内进行测试，该接收器可用于本项目，将成为理想的测试台。我们的重点是在原型仪器的背景下展示这些延迟线的技术准备水平，从而解决集成问题以及纯技术开发。

In this project we seek to exploit a novel liquid crystal technology, whichallows a controllable true time delay to be applied to an RF signal offrequencies up to tens of Giga-Hertz. The basic technology has already beendemonstrated and has a wide variety of applications. We now intend to use thistechnology to construct a real astronomical demonstration system for delaylines and show that these can be integrated into the beam-forming module of anexisting Phased Array Feed (PAF) instrument, dramatically improving itscapabilities. PAFs are an essential next step for radio astronomy. They offer thepossibility of increasing a telescope's Field-of-View (FoV), ofimproved calibration and of allowing operation up to higherfrequency. PAFs have been implemented in instruments such as PHAROSand can achieve these goals, but over a narrow bandwidth due to theuse of phase shifters in the beam-former hardware. In this project weseek to implement a true time delay beam-former, which will allow thewhole available bandwidth to be used. This will make use of noveltechnology - liquid crystal stripline whose dielectric constant canbe varied by application of an AC voltage. We propose a two yearprogramme during which we will produce a PAF module using a set oftrue-time delay units that will be tested within the PHAROS receiver,which is available for use on this project and will make an idealtest-bed. Our focus is on demonstrating the Technology Readiness Levelof these delay lines in the context of a prototype instrument, therebyaddressing integration issues as well as pure technology development.