Variable Dielectric Delay Lines in Liquid Crystals for Phased Array Feeds

In this project we seek to exploit a novel liquid crystal technology, which
allows a controllable true time delay to be applied to an RF signal of
frequencies up to tens of Giga-Hertz. The basic technology has already been
demonstrated and has a wide variety of applications. We now intend to use this
technology to construct a real astronomical demonstration system for delay
lines and show that these can be integrated into the beam-forming module of an
existing Phased Array Feed (PAF) instrument, dramatically improving its
capabilities.

PAFs are an essential next step for radio astronomy. They offer the
possibility of increasing a telescope's Field-of-View (FoV), of
improved calibration and of allowing operation up to higher
frequency. PAFs have been implemented in instruments such as PHAROS
and can achieve these goals, but over a narrow bandwidth due to the
use of phase shifters in the beam-former hardware. In this project we
seek to implement a true time delay beam-former, which will allow the
whole available bandwidth to be used. This will make use of novel
technology - liquid crystal stripline whose dielectric constant can
be varied by application of an AC voltage. We propose a two year
programme during which we will produce a PAF module using a set of
true-time delay units that will be tested within the PHAROS receiver,
which is available for use on this project and will make an ideal
test-bed. Our focus is on demonstrating the Technology Readiness Level
of these delay lines in the context of a prototype instrument, thereby
addressing integration issues as well as pure technology development.

Below is a summary of beneficiaries of the proposed research; this is explored in more detail in the Pathways to Impact document. The main beneficiaries are:

- Business/Industry:

The most exciting areas for impact actually lie outside astronomy and this project should be seen as the first step towards realising the potential for LC delay lines operating at higher frequencies and wider bandwidths with a wide variety of applications. The technology has many attractive features: liquid crystal devices are a fundamentally low cost technology with well known manufacturing techniques for volume commercial applications; devices are low power and operate at short wavelengths with the result that components are physically small and hence cheap; at RF-frequencies beyond the capabilities of silicon devices liquid crystal offers an attractive alternative to implementing delays compared with expensive chips developed from e.g. GaAs. Possible future applications include: anti-collision radar; autonomous automobile driving; high frequency telecommunications; medical imaging technologies; security scanners.

There will also be a direct benefit to industry through the development and production of the hardware for the astronomical instruments we envisage being enabled by this project, in terms of financial return, valuable knowledge exchange and IP production.

- Academic:

The areas that will benefit from this project are: radio astronomy technology development and enabling of future experiments; electrical engineering; communication engineering; antennas and propagation engineering. (See Academic Beneficiaries for further details).

- General Public:

The new experimental areas that will be opened up by this project include the deeper understanding of structure formation in the Universe, which has been proven to be of great interest to the General Public as a whole.

- Schools:

Astronomy outreach inspires school age students and so enthuses them to become the next generation of scientists and engineers.