CURALF

Abstract

Space launches have been steadily increasing over the years as satellites are being used in various applications such as communication, military, and science. The costs of launching satellites are still high and depend on the dimensions and weight of the satellite. With the advancement in the field of autonomous robotics and telecommunications, the need for multiple satellites in swarms and constellations is also growing. Cubesats have emerged as an alternative for these issues as they provide a low cost and compact solution. After the successful launch of NCLE (Netherlands China Low-Frequency explorer), a radio astronomy payload in the Chang'e 4 mission, efforts are being made to reduce the size of the payload to meet the cubesat standards. This work aims at investigating the design and implementation of a sensitive radio receiver for low-frequency radio astronomy from the lunar orbit with a cubesat platform. The aim is to study the practical aspects involved in realizing the design and improving the sensitivity of the instrument. The science objectives are similar to that of the NCLE payload which includes the frequency band of 80 kHz-80 MHz with high dynamic range and linearity. The thesis is a step further in the project OLFAR which aims to have a swarm of satellites in the lunar orbit to perform long-baseline interferometry at low frequencies. This work focuses on the analog signal chain of the payload which contains the antenna, low noise amplifier, filters, and the ADC. For the design of the antenna, the antenna length, efficiency, and IXR of three antenna configurations have been presented. As radio frequency interference poses a problem during the design of the amplifier chain, the effects and coupling mechanisms of RFI have also been studied. Limits on all internal and external instruments for radiated emissions have been set for the design to be sky noise limited. The amplifier design takes the science cases into account and is designed to achieve the required sensitivity, using a structured electronic design approach. The implementation of the amplifier chain was done with discrete components at ASTRON (Netherlands Institute for Radio Astronomy) and measurement results have also been discussed at the end.