Innovative antenna design for radio astronomy in space

Following the Big Bang model, the chronological timeline of the Universe started out with the so-called Dark Age, an epoch or era where stars had yet to form. After this the first stars formed, which in turn led to the formation of planets and galaxies alike.

Our night sky might be dominated by the presence of countless stars and galaxies of varying brightness in the visible spectrum. In the midst of these light signals that reachi our planet every single second of every day though are signals from the Dark Age of the Universe.

Red shift

A host of astronomy instrumentation, both Earth-based and in-orbit, have demonstrated a red shift in a large part of the Universe due to the expansion of the Universe, where red shift means that light waves are stretched out so that their wavelengths are shifted towards those of red light. It is these red-shifted light signals that are associated with the Dark Age.

Detection of these signals allows us to peer in the past history of the Universe. By inverting the process of the expansion and thus looking into the past, it is theoretically possible to gather information on the Universe when it was much smaller and had not expanded to its current size.

Using Earth-based radio astronomy instrumentation, it is impossible to receive these signals without interference from man-made technologies, as well as the fact that our ionosphere distorts and completely blocks signals below 30 and 10MHz, respectively.

The only solution is to move the detectors to space, for which new techniques and instrumentation must be designed and must be sensitive to these extremely weak signals that have travelled for about 13.8billion years to reach Earth.

New antennas

In his PhD research, Niels Vertegaal looked at new designs for antennas to receive these very faint signals from the Dark Age epoch. When making any device intended for launch into space, it’s important to take into consideration size and weight requirements, which should be minimized for cost reasons.

Shape Memory Alloy

However, large sensitive antennas are needed to receive the signals from space. Therefore Vertegaal and his colleagues first solution involves the use of Shape Memory Alloy (SMA). Two antennas were designed using this material, which can be trained to a certain shape after which it can be manipulated to fit within 0.5U~(10x10x5~cm).

By heating the material, the material will return to its original trained shape thereby increasing in height by 300% and 700% for the Horn Antenna and Yagi-Uda Design respectively.

Inflatable

The second solution is the use of inflatable antennas. These, as with SMA, can be packed very efficiently during launch while being deployed to a large volume when in space with a minimal pressure difference due to the vacuum and microgravity conditions.

The designed antennas were made using polymide with copper clad laminate with a total thickness 27 um. The realized antenna matches simulation within about 1dBi.

Packaged, the antenna fits within a box with approximate dimensions of 10x10x10cm, while deployed it expands to a volume of roughly 1x1x0.2m. Due to this packaging efficiency and design freedom, it has a high potential to realize radio astronomy in space.

To test the concept of inflatable antennas, a flight system was developed for use on a high altitude balloon. The flight system took care of the deployment and performed RF Measurements in the air. Based on the experiences using the method, it is beneficial for future designs to be tested using a comparable cost-effective way.

Want to know more?

Want to know more about the flight system testing for the deployment of the high altitude balloon?

Check out this article on the TU/e website, and also an article on the Cursor wesbite.

Title of PhD thesis: Innovative Antenna Design for Radio Astronomy in Space: Looking back in time. Supervisors: Mark Bentum and Hamid Pourshaghaghi.