A SMART antenna can control its main radiation pattern direction and shape. This is achieved by using a fully active system in which each antenna element is controlled independently of one another. This technique requires RF control for each antenna, which introduces high complexity and cost. Cobham Technical Services has pioneered lower cost solutions that only require a single active element.
A SMART antenna can improve the quality of a wireless link by providing interference suppression and/or range enhancement. The benefits of using SMART antennas in a wireless system are improved capacity, higher data rates and better spectrum efficiency. SMART antenna technology can also be applied to WIMAX and mobile signal detection applications.
SMART systems rely on the interaction of closely spaced antennas to produce radiation pattern peaks or nulls in a desired direction. Antennas operating in close proximity have inherently different characteristics to an isolated element. Therefore the design of these systems is more challenging. Cobham has developed techniques to efficiently analyse multi-antenna systems and the interaction with the RF control circuitry. We have demonstrated the design concept by building a prototype dual-band WLAN system.
Conventional SMART arrays are band limited by the spatial (or electrical) separation of the elements, since these systems rely on high levels of mutual coupling for pattern formation. Cobham has developed an array that can provide pattern adaptation over extremely wide bandwidths, using novel antenna and switching techniques. This system has been operated over a 3:1 bandwidth.
Many future applications will benefit from this type of technology due to improved interference suppression and/or range enhancement, and it is envisaged that multi-antenna systems will have an increasingly important role in future wireless communication systems.