An important element of MFM is the convention used for describing 3-D geometry. This is particularly important to when placing devices, using antenna arrays, and working with channel objects.

MFM uses azimuth and elevation angles to describe 3-D angular information.

Azimuth—shown below as $\theta$—is defined as the angle from the y-axis to the projection of the vector of interest onto the x-y plane. Azimuth angles range from $-\pi$ to $\pi$.

Elevation—shown below as $\phi$—is defined as the angle from the x-y plane to the vector of interest. Elevation angles range from $-\pi/2$ to $\pi/2$.

Explicitly, the 3-D geometry can be summarized as follows, where $r$ is the radial distance, $\theta$ is the azimuth angle, and $\phi$ is the elevation angle.

A vector of length $r$ in the azimuth-elevation direction $(\theta,\phi)$ can be converted to Cartesian components $(x,y,z)$ as

A vector having Cartesian components $(x,y,z)$ can be described as having length $r$ in the azimuth-elevation direction $(\theta,\phi)$ via

Uniform linear arrays are created along the x-axis by default, meaning that an azimuth of 0 degrees is directly in from the array (broadside).

Uniform planar arrays are created in the x-z plane by default, meaning that an azimuth of 0 degrees and elevation of 0 degrees is broadside.