Extended hemispherical lens explained

The extended hemispherical lens is a commonly used lens for millimeter-wave electromagnetic radiation. Such lenses are typically fabricated from dielectric materials such as Teflon or silicon. The geometry consists of a hemisphere of radius on a cylinder of length, with the same radius.

Scanning performance

When a feed element is placed a distance off the central axis, then the main beam will be steered an angle off-axis. The relation between and can be determined from geometrical optics:^[1]

(d)/(L) = \tan \gamma. This relation is used when designing focal plane arrays to be used with the extended hemispherical lens.

See also

• Luneburg lens
• Fresnel lens
• Lens antenna

Notes and References

1. Frid . Henrik . Closed-Form Relation Between the Scan Angle and Feed Position for Extended Hemispherical Lenses Based on Ray Tracing . IEEE Antennas and Wireless Propagation Letters . 2016. 15 . 1963 . 10.1109/LAWP.2016.2545858 . 2016IAWPL..15.1963F . 24384665 .