Fig. 17
From: High precision hybrid RF and ultrasonic chirp-based ranging for low-power IoT nodes

Polar plot of the measured, relative, XY directionality of the Fostex FT17H tweeter @25 kHz in non-anechoic chamber
From: High precision hybrid RF and ultrasonic chirp-based ranging for low-power IoT nodes
Polar plot of the measured, relative, XY directionality of the Fostex FT17H tweeter @25 kHz in non-anechoic chamber