Meaning
Electromagnetic radiation propagating as a highly concentrated beam with a symmetric intensity profile that tapers off from the central axis characterizes the primary mode of laser and high-frequency antenna emissions. A gaussian beam represents the fundamental transverse mode where the electric field amplitude has a Gaussian distribution across the beam cross-section. This profile minimizes divergence as the wave travels through free space.
Spatial Distribution
The intensity of the radiation is highest at the center of the beam and drops off exponentially with the square of the radial distance from the axis. Within a gaussian beam, the beam width is defined as the radius where the intensity drops to a fraction of its peak value. This parameter determines the spatial resolution and power density at the target surface.
Optical Focus
Lenses are used to manipulate the shape of the propagating wavefront. When focusing a gaussian beam, the wave converges to a minimum beam waist of finite size. This waist is dictated by diffraction.
Wavefront Profile
High-frequency millimeter-wave systems treat their radiated fields as propagating beams to optimize antenna feed designs. Measuring a gaussian beam requires precise scans of the phase and amplitude across the aperture of the feed horn. System designers use these measurements to optimize the coupling efficiency between the feed horn and the focusing lenses.
This optimization maximizes the gain of the antenna system while minimizing spillover losses and secondary reflections in the enclosure.
