A study on radiation pattern of DBF antenna with bit number restriction

This paper describes an experimental study on the performance limitation of Digital Beam Former (DBF) antenna caused by bit number restriction. The study focuses on the evaluation of the relationship between radiation pattern of DBF antenna and quantization bit number of A/D converter. Two experiments were performed by using a prototype RX DBF/Digital Channelizer (DBF/DC). At first, we evaluated DBF/DC input-output (I/O) linearity and dynamic range characteristics, and it is confirmed that the bit number restriction function of the RX DBF/DC properly works. Then, we measured the radiation pattern of the 16-element array antenna integrated with the RX DBF/DC. It was observed that the radiation patterns with small bit number (6bit) were distorted compared with those with high bit number (8bit) for both one-element antenna and 16-element array. From these observations, we confirmed that bit number restriction affects the performance of DBF antenna.