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.

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[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.

Extended hemispherical lens

Scanning performance

See also

References