Position Detection of Distant Human Respiration Using 4×4 Phased Antenna Array

This paper proposes a respiratory detection and localization system using a Phased Array Antenna (PAA). In this system, we used 4×4 phased array antenna with Left-Handed Transmission Line (LHTL) type phase shifter, which has advantages on miniaturization and simple control. The whole scanning area was 3 m × 3 m and the area was divided into 4 squares whose individual area was 1.5 m × 1.5 m. Beam steering of the PAA was conducted for four directions (up down left right) from the center with +30°, -30° bias angle to scan these individual areas. Using the fabricated PAA and respiration detection algorithm, this radar system was able to locate the position of human respiration and its frequency with 94 % accuracy from 3.5 m distance.