phitheta2azel

Convert angles from phi/theta form to azimuth/elevation form

Syntax

AzEl = phitheta2azel(PhiTheta)

AzEl = phitheta2azel(PhiTheta,RotAx)

Description

AzEl = phitheta2azel(PhiTheta) converts the phi/theta angle pairs to their corresponding azimuth/elevation angle pairs.

AzEl = phitheta2azel(PhiTheta,RotAx) also specifies the choice of phi-theta angle convention using RotAx.

Examples

Convert Phi-Theta Coordinates to Azimuth-Elevation Coordinates

Find the azimuth-elevation representation for φ = 30° and θ = 0°. Use the phi-theta convention with φ defined from the y-axis to the z-axis, and θ defined from the x-axis toward the yz-plane.

azel = phitheta2azel([30;10])

azel = 2×1

    8.6822
    4.9809

Rotate and Convert Phi-Theta Coordinates to Azimuth-Elevation Coordinates

Find the azimuth-elevation representation for φ = 30° and θ = 0°. Use the phi-theta convention with φ defined from the x-axis to the y-axis, and θ defined from the z-axis toward the xy-plane.

azel = phitheta2azel([30;10],false)

azel = 2×1

   30.0000
   80.0000

Copyright 2012 The MathWorks, Inc..

Input Arguments

PhiTheta — Phi-theta angle pairs

two-row matrix

Phi and theta angles, specified as a two-row matrix. Each column of the matrix represents an angle in degrees, in the form [phi; theta].

Data Types: double

RotAx — Phi-theta angle convention selection

true (default) | false

Phi-theta angle convention selection, specified as true or false.

• If RotAx is true, the phi angle of a direction vector is the angle from the z-axis to the projection of the vector into the yz-plane. The theta angle is defined from the x-axis to the direction vector. Positive values are toward the yz-plane.

• If RotAx is false, the phi angle is defined from the x-axis to the projection of the direction vector in the xy-plane. The angle is positive in the direction of the y-axis. The theta angle is defined from the z-axis to the direction vector and is positive in the direction of the xy- plane (see Alternative Definition of Phi and Theta Angles ).

Data Types: logical

Output Arguments

AzEl — Azimuth-elevation angle pairs

two-row matrix

Azimuth and elevation angles, returned as a two-row matrix. Each column of the matrix represents an angle in degrees, in the form [azimuth; elevation]. The matrix dimensions of AzEl are the same as those of PhiTheta.

More About

Azimuth and Elevation Angles

The azimuth angle of a vector is the angle between the x-axis and the orthogonal projection of the vector onto the xy plane. The angle is positive in going from the x axis toward the y axis. Azimuth angles lie between –180 and 180 degrees. The elevation angle is the angle between the vector and its orthogonal projection onto the xy-plane. The angle is positive when going toward the positive z-axis from the xy plane. By default, the boresight direction of an element or array is aligned with the positive x-axis. The boresight direction is the direction of the main lobe of an element or array.

Note

The elevation angle is sometimes defined in the literature as the angle a vector makes with the positive z-axis. The MATLAB^® and Phased Array System Toolbox™ products do not use this definition.

This figure illustrates the azimuth angle and elevation angle for a vector shown as a green solid line.

Phi and Theta Angles

The phi angle (φ) is the angle from the positive y-axis to the vector’s orthogonal projection onto the yz plane. The angle is positive toward the positive z-axis. The phi angle is between 0 and 360 degrees. The theta angle (θ) is the angle from the x-axis to the vector itself. The angle is positive toward the yz plane. The theta angle is between 0 and 180 degrees.

The figure illustrates phi and theta for a vector that appears as a green solid line.

The coordinate transformations between φ/θ and az/el are described by the following equations

$$\begin{array}{l}\sin el=\sin \varphi \sin \theta \\ \tan az=\cos \varphi \tan \theta \\ \cos \theta =\cos el\cos az\\ \tan \varphi =\tan el/\sin az\end{array}$$

Alternative Definition of Phi and Theta Angles

The phi angle (φ) is the angle from the positive x-axis to the vector’s orthogonal projection onto the xy plane. The angle is positive toward the positive y-axis. The phi angle is between 0 and 360 degrees. The theta angle (θ) is the angle from the z-axis to the vector itself. The angle is positive toward the xy plane. The theta angle is between 0 and 180 degrees.

The figure illustrates φ and θ for a vector that appears as a green solid line.

$$\begin{array}{l}\varphi =az\\ \theta =90-el\\ az=\varphi \\ el=90-\theta \end{array}$$

This transformation applies when RotAx is false.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

Does not support variable-size inputs.

Version History

Introduced in R2012a