Extended hemispherical lens

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 $R$ on a cylinder of length $L$ , with the same radius.

Scanning performance

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

{\frac {d}{L}}=\tan \gamma .

This relation is used when designing focal plane arrays to be used with the extended hemispherical lens.

References

^ Frid, Henrik (2016). "Closed-Form Relation Between the Scan Angle and Feed Position for Extended Hemispherical Lenses Based on Ray Tracing". IEEE Antennas and Wireless Propagation Letters.

[1] Frid, Henrik (2016). "Closed-Form Relation Between the Scan Angle and Feed Position for Extended Hemispherical Lenses Based on Ray Tracing". IEEE Antennas and Wireless Propagation Letters.

[1]

Scanning performance

See also

References