The Design And Study Of High Sensitivity And Ultra-wideband Radio Telescope Feed Horn

With the development of the technology,the mysterious universe attracts humans to explore constantly.The radio telescope is the main instrument for humans to explore the universe.So its performance is particularly important.Sensitivity and bandwidth are two important indicators of the radio telescope receiving system.Sensitivity determines the ability of a telescope to receive weak signals and the bandwidth determines the scope of scientific exploration.The traditional one octave bandwidth receiving system is far from meeting the needs of various new scientific explorations.Therefore,high sensitivity and ultra-wideband is an inevitable development trend of the new generation of radio telescope receiving systems.Feed horn is one of the most important parts of the receiving system,the radiation pattern of which largely affects the sensitivity and its bandwidth also limits the bandwidth of the receiving system.So,it has always been a research hotspot in the direction of radio astronomy.For the commands of new generation of radio telescope,this paper do the research on high performance feeds and a 3.5 octave bandwidth horn feed is presented,fabricated and measured.The corresponding theoretical analysis and design of the feed is carried out.A fast design method is used to optimize the feed.To make the sensitivity optimum,the particle swarm optimization(PSO)algorithm is used to find a trade-off between aperture efficiency and radiation spill-over.The feed is based on quad-ridged horn and it is fitted by big amounts of spline points.The desired radiation pattern produced by higher-order modes of different ratios through the discontinuous structure of the spline profile.The measured results show that the return loss of two ports are greater than 10 dB and the isolation is greater than 30 dB.The average aperture efficiency in a 62°15m prime focus parabolic reflector antenna is greater than 63%,the noise temperature varies form 5 K to 30 K and the average sensitivity is greater than 4.6m~2/k within the working frequency band.The design fills the domestic blank of high performance feed in China.In addition,the feed can also be simply scaled to other operating bands by applying the similar configuration which has a great significance on the future design of radio telescope feeds.