Sector Antennas for Millimetre Wave Applications, 38-40 GHz.
A type of lens antenna with a null filled elevation pattern was developed. The intended use is for base stations for point-to-multi-point applications. This is also called a ‘sector antenna’ because it illuminates a 90° sector in azimuth .
Millimetre wave frequencies above 30 GHz offer operators ample bandwidth. The design example shown is for the 38.6-40 GHz band.
The lens antenna has excellent characteristics for this application:
Type: lens-horn with null filling for elevation beam shaping.
Polarization: horizontal or vertical, separate antenna variants.
Frequency 38.6 – 40 GHz
Gain 22 dBi
Elevation half power beamwidth 3°
Azimuth half power beamwidth 60°
Front-to-back ratio, typical >30 dB
Return Loss > 17 dB
Outline dimensions (mm): 370 x 270 x 14
(inches): 14.5 x 10.6 x 0.6
Example Radiation Patterns.
The antenna would typically be mounted on a mast and tilted slightly downwards. The left hand side of the pattern represents space above the horizon, where no radiation is required. The right hand side represent space below the horizon, and the ground near to the mast. In this region we want to eliminate nulls which would lead to ‘not spots’ (outages in coverage).
Further reading on Lens Antennas:
J. Thornton and K.C.Huang, “Modern Lens Antennas for Communications Engineering”, Wiley-IEEE, published April 2013
Antennas Research 2010 - 2016