Conventional high-frequency antennas are often cumbersome to manufacture. For example, antennas designed for 100 GHz bandwidths typically use machined waveguides as feed structures, requiring expensive micro-machining and hand-tuning. Not only are these structures difficult and expensive to manufacture, they are also incompatible with integration to standard semiconductor processes.
As is the case with individual conventional high-frequency antennas, beam forming arrays of such antennas are also generally difficult and expensive to manufacture. Conventional beam forming arrays require complicated feed structures and phase-shifters that are impractical to be implemented in a semiconductor-based design due to its cost, power consumption and deficiency in electrical characteristics such as insertion loss and quantization noise levels. In addition, conventional beam forming arrays become incompatible with digital signal processing techniques as the operating frequency is increased. For example, at the higher data rates enabled by high frequency operation, multipath fading and cross-interference becomes a serious issue. Adaptive beam forming techniques are known to combat these problems. But adaptive beam forming for transmission at 10 GHz or higher frequencies requires massively parallel utilization of A/D and D/A converters.
Beam forming techniques are useful in applications such as automotive collision avoidance. The beam from such a system should project forward from the vehicle to detect oncoming hazards. However, esthetic and aerodynamic concerns limit the opportunity to mount an antenna array on the vehicles. A convenient location would be either in the headlights or the windshield. However, such a mounting must not interfere with the vision of the driver or the headlight intensity. Accordingly, there is a need in the art for a semiconductor-based antenna array compatible with transparent substrates.