ASSA Radio Astronomy Group

Introduction

You can only make a dish antenna so big. Physically, this is a true statement. The limit is about 100 metres in diameter, if you could afford to engineer the precision metalwork across an area that large, hold it down with enough concrete so it didn't blow away in a storm and be able to steer it and focus where you wanted to observe. Fortunately, there is an alternative method of enlarging the effective aperture of a radio telescope. It's called synthesis imaging interferometry. These instruments can be large, complex and expensive such as the Long Baseline Arrays operated by government research agencies around the world. They can also be small, simple and inexpensive created by clever individuals, a couple of examples are shown here and here.

Our High Frequency Interferometer Project

We are currently planning and building a multisite, multiuser, high frequency interferometer (HFI). The HFI will be somewhere between the two examples given in the previous paragraph. The sites will be remote from each other, using an advanced software defined receiver which is phase locked to all receivers in the network with GPS common view techniques. Some sites will be located off the mains grid so efficient hardware and support infrastructure will be used to reduce power consumption, where possible. This will probably mean that only data collection will be carried out at each site, correlation and processing will be carried out at a central facility.