Quasi Optical Systems for mm-Wave Antennas


In the last few years, there has been a growing interest in millimetre- and submillimetre-wave systems. In fact, shorter wavelengths permit the use of components smaller and lighter than the ones employed in microwave systems thus enabling new innovative applications and solutions, especially for military and space-borne systems where size and weight are a prime concern. Typical examples of these applications include the realization of high data-rate links in pico-cellular networks, local multipoint data services, a radars, inter-satellite communications, deep space observation, imaging for security and medical applications.

Electronic circuit design at such high frequencies presents several difficulties which cannot be dealt with using conventional design methods.

The main obstacles in the development of millimetre and submillimetre wave systems are power losses in beam-forming networks and the lack of efficient and inexpensive medium- and high-power sources. One of the most promising solutions for these two obstacles is the development of quasi-optical that have recently been introduced for power generation at millimetre wave frequencies. The reason for the growing attention given to quasi optical systems is that they make it possible to combine the power of solid-state devices on a large scale in free space, yielding significant improvements in terms of power output levels, power added and power combining efficiencies.

In this presentation some basic features of quasi optical systems will be described trying to envision the impact of these techniques in future mm-wave antennas.