Algorithm 1. PF algorithm for 3D emitter location using azimuth and elevation measurements.

1. At each measurement point $i=1, 2, \dots , N$, calculate the parameters necessary to determine the mean dimensions of the cuboid search space, i.e., $V{x}^{min}$, $V{x}^{max}$, $V{y}^{min}$, $V{y}^{max}$, $V{z}^{min}$, and $V{z}^{max}$, by solving Equations (15)–(25);

2. After collecting all azimuth and elevation angle measurements, generate a set of $P$ particles uniformly distributed within the cuboid search space, according to Equations (26)–(28);

3. Compute azimuth and elevation angle predictions, i.e., ${\theta }_i^p$ and ${\phi }_i^p$, for each particle, $s_p$, according to Equations (29) and (30);

4. Compute the weight, $w_p$, of each particle, $s_p$, according to Equation (31);

5. Obtain the estimate of the emitter location, ${\widehat{p}}_e$, by Equation (32).