The Synthetic Measurement Method for the Antenna and Receiver in a Radio Antenna Array

This paper first reviews the Y factor method to measure the antenna performances of radio telescopes on site. We point out that with a few improvements and using the telescope receiver also as the receiver for performance measurement, the antenna and receiver can both be measured. The paper describes such a synthetic measurement method of performances of the antenna and receiver in a radio antenna array. The method is proceeded that the analog receiver input is connected to the 50Ω terminal and noise source, and the antenna is pointed toward the cold sky and the sun, all in proper alternating order. Four sets of radio powers are consequently measured and recorded (P₅₀, P_NS, P_SKY, and P_SUN ). The formulae of the gain and noise temperature of the antenna and receiver can be derived according to the method.T_R=T_NS-T₅₀(P_NS/P₅₀)/P_NS/P₅₀-1, G_R=P₅₀(P_NS/P₅₀-1)/kB(T_NS-T₅₀), T_S=P_SKY(T_NS-T₅₀)/P₅₀(P_NS/P₅₀-1)-T_SKY, and G_A=8πk(T_NS-T₅₀)(P_SUN-P_SKY)/Sλ²P₅₀(P_NS/P₅₀-1) We have measured and calculated the corresponding parameters, and have compared them to the design specifications. We also discuss the pattern method to measure the antenna gain on site.