Radio quiet and radio notification zones characteristics for radio astronomy in medium densely populated areas and humid tropical countries

This study proposes general criteria to identify a radio quiet zone (RQZ) and a radio notification zone (RNZ) for the installation of a radio astronomical observatory on-site and safeguard the radio astronomy spectrum specifically in tropical regions. This study focuses on areas with a medium population density. Most RQZs selected in the world are mainly located in regions with a low population density, whereas this work studies the radio frequency interference (RFI) environment in humid tropical regions that have not been studied. The humidity in the tropical regions has a significant effect on radio signal, and this provides a unique perspective to the study. This study implements an algorithm to model the RFI level by considering important humidity factors. The ideal sites are chosen based on the RQZs criteria, whereas the realistic sites are based on the RNZs criteria. In Malaysia, four ideal and another four realistic candidate sites were identified, and the on-site RFI level measurement was conducted. From this study, Kuala Tembeling site is suggested as the RQZ and the Jelebu site as the RNZ in Malaysia.