Project Overview

Controlling and suppressing the spurious emissions of small satellite transmitters in radio astronomy bands is essential to prevent debilitating levels of radio interference in the very near future (as close as the 2030s). Efforts by the International Telecommunication Union (ITU) have been made to protect radio astronomy from such spurious emissions through Recommendation ITU-R RA.1513 (2015). However, a concerning precedence has already been set by many current examples of small satellites that have been observed to exhibit unintended and out-of-band emissions that far exceed the limits set out by these regulations. Secondly, the radio astronomy community, in particular low frequency radio astronomers, are also concerned current regulations (if met) are inadequate to achieve their intended goal.  

Controlling and suppressing spurious emissions to a sufficient degree to protect current and future low frequency radio astronomy telescope ventures is challenging. Firstly, determining the maximum acceptable level of spurious emissions requires detailed knowledge of the radio telescopes science use cases and its system specifications. Secondly, then achieving these stringent spurious emissions limits necessitates sufficient attenuation of noise and harmonics. For small satellites, high efficiency switch-mode power amplifiers are essential to enable most small satellite missions due to their low power budget. However, switch-mode amplifiers achieve high efficiency at the cost of introducing significant noise and harmonics at the output. As a direct consequence, implementing conventional filtering techniques to address spurious emissions requirements would result in a prohibitive reduction in transmitter efficiency for small satellite applications. Therefore, a new power amplifier design method to suppress spurious emissions in the radio astronomy band whilst retaining high efficiency operation is highly desirable. High efficiency power amplifier design with integrated targeted filtering of key frequency bands to meet the specific spurious emissions limits has the potential to directly address this need whilst at the same time maximizing efficiency.

Aims

To this end, there are two key project aims. The first being to define new spurious emissions limits that protect the science use cases of current and future low frequency radio telescopes, with a focus on the Murchison Widefield Array (MWA) and the Square Kilometre Array Low-Frequency (SKA-Low). Subsequently, the second aim of this project is to develop a new method to design highly efficient power amplifiers for small satellite transmitters that suppresses spurious emissions in radio astronomy bands and meets the new spurious emissions limits.

Objectives

The objectives of this project are: 
1. To determine the telescope noise floor requirements to enable low frequency radio astronomy observations based on MWA and SKA-Low science use cases and system specification; 
2. To use this noise floor requirement to define new low frequency radio astronomy spurious emissions limits for low Earth orbiting (LEO) satellites; 
3. To explore new methods to design highly efficient power amplifiers for small satellite transmitters that satisfy the new low frequency radio astronomy spurious emissions limits; 
4. And to develop a generalized design technique for generating such power amplifiers for small satellite transmitters that can be tailored to specific small satellite applications and transmitting frequencies.

Significance 

This project is significant because it has the potential to present a solution that permits and facilitates the inevitable growth of small satellites, whilst at the same time enabling low frequency radio astronomy using the MWA and SKA-Low. Specifically, this project has the potential to define new emissions limits for LEO small satellites that are compliant with radio astronomy. If enforced by a governing/regulating body such as the ITU, these emissions limits could successfully protect the science cases of current and future low frequency radio telescopes including the MWA and SKA-Low. This project also has the potential to provide the small satellite community with a practical design technique for highly efficient power amplifiers that meets the new emissions limits. The idea is that this design technique can be readily tailored to their specific application and transmitting frequency. Therefore, this project aims to benefit both small satellites and low frequency radio astronomy.

The successful candidate will join an active engineering group working on highly efficient RF power amplifiers for small satellites at the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR), a joint venture with the University of Western Australia comprising around 200 staff and students. The engineering group have close connections to numerous international and domestic expert collaborators. All relevant simulation and electronic design software, as well as a suitable desktop and server access is provided. For prototype measurement and verification, access to our well-established RF labs, which notably includes access to several network analyzers, spectrum analyzers, oscilloscopes, as well as a semi-anechoic chamber and a GTEM cell. There will also be plenty of opportunity to present results at international and domestic conferences through funding from Curtin including extra funds if the industry internship is undertaken.

An internship may be available for this project. ICRAR/Curtin is strategically positioned in the nexus of the radio astronomy and radio frequency engineering with long-standing collaborative ties with research end-user such as CSIRO and SKAO. To this end, we have already established contact with Dr Balthasar Indermühle, a Principal Experimental Scientist at CSIRO Space & Astronomy, who indicated that a 60-day internship could be arranged. In addition, ICRAR/Curtin is well supported by an experienced Translation and Impact team who will assist in putting a collaborative internship agreement in place with the hosting institution.

• Future Students

• Faculty of Science & Engineering
  • Science courses
  • Engineering courses

• Higher Degree by Research

• Australian Citizen
• Australian Permanent Resident
• New Zealand Citizen
• Permanent Humanitarian Visa
• International Student

• Merit Based

The annual scholarship package, covering both stipend and tuition fees, amounts to approximately $70,000 per year.

In 2024, the RTP stipend scholarship offers $35,000 per annum for a duration of up to three years. Exceptional progress and adherence to timelines may qualify students for a six-month completion scholarship.

Selection for these scholarships involves a competitive process, with shortlisted applicants notified of outcomes by November 2024.

1

All applicable HDR courses.

Preferred applicants’ skill set would include:  
• Experience in high efficiency switch-mode RF power amplifier design; 
• Experience in reducing/controlling spurious emissions in active devices,  
• And experience in high efficiency RF filter design. 
This project would be highly suited, however not limited to, an applicant that has some prior experience with and knowledge of low frequency radio telescopes.

 

Please send your CV, academic transcripts and brief rationale why you want to join this research project via the HDR expression of interest form to the project lead researcher, listed below. 

You must be enrolled in a Higher Degree by Research Course at Curtin University by March 2025.

Project Lead: Associate Professor Adrian Sutinjo