An Active Antenna Subarray for the Low-Frequency Radio Telescope GURT—Part II: Numerical Analysis and Experiment

This second part of two articles' sequence presents the detailed numerical analysis of electrical and noise parameters of a subarray of the Giant Ukrainian Radio Telescope (GURT) designed for operation in the frequency range of 8-80 MHz. The theoretical model of the subarray and calculation technique of its parameters developed in the first part is used. Frequency behaviors of the absorption area, radiation efficiency, and system noise temperature budget of the subarray are studied. Special attention is paid to the subarray sensitivity given in terms of sky noise dominance (SND) and system-equivalent flux density (SEFD). The calculation results show that strong mutual coupling between subarray elements enables a significant increase in the subarray SND and enhancing overall its performance. The frequency dependences of the system noise temperature for 23 beams of the subarray, obtained by in situ measurements, are presented. A good agreement between the measured and calculated results well enough validates the subarray theoretical model.