QuinStar Technology’s QLA series lens antennas are available with apertures ranging from 3 to 12 inches (76-300 mm) for any frequency in the 18-140 GHz range. These antennas consist of a lens which is fed (illuminated) by a specially-designed feed horn. They have inherently low sidelobes, particularly in comparison to Cassegrain reflector antennas, as there is no blockage of the main beam by a subreflector or feed structure. Specially designed lenses, when combined with high performance feeds, produce high gain, precise beam patterns and efficiency comparable to the best reflector antennas, even at high millimeter wave frequencies. They operate over a fairly wide frequency range, which is generally determined by the characteristics of the input circular waveguide and feed horn. Standard antennas are focused at infinity (far field). However, custom designs focused at a finite range, generally 4 to 40 inches (0.1 to 1 meter) from the lens, can be provided.
The length of the antenna is nearly equal to its lens diameter (f/D = 1) to achieve a reasonable size with optimal performance, although other f/D ratios are available as special products. The feed horn for these antenna may be either conical (standard product) or scaler feed horn (symmetrical, low sidelobe). Typical lenses have a smooth external surface and operate virtually independent of frequency. However, for specific narrowband applications, the lens can be zoned to reduce size and weight. The interface to these antennas is a circular waveguide of suitable diameter for the center frequency. However, an integral circular-to-rectangular waveguide transition is available as well as a variety of other options including a detachable circular-to¬-rectangular transition, orthomode transducer (OMT), circular polarizer (fixed or adjustable) and mountable bore-sighted telescope.
QuinStar can also provide antennas with dual-polarization capability and dual-frequency band operations as customized products.
Lens antennas are most practical in 3 to 12 inch (75 to 300 mm) diameters in the 18 to 140 GHz frequency range for applications where high performance, particularly low sidelobes, is critical. They can also be produced at a fairly low cost in large quantity. In addition, the antenna housing can be used as an enclosure for other components, system electronics or the entire system.