A new method for the design of active dipole-transistor elements using feedback control

Millimetre wave technology has become the focus of many applications which would benefit from the commonly cited advantages of the shorter wavelength radiation. Such desirable properties include smaller dimensioned components, wider available bandwidth and better resolution for radar and imaging applications. At the heart of this technology is the need for a compact, cost effective and high power millimetre wave source. The method of spatial power combining is one option which is currently being researched. It is the process of summing the power output of many oscillators in free space using radiating elements. There are 3 main categories of spatial power combiners: resonator based structures which use an optical cavity to synchronise the frequency and phase of the oscillators; active antenna arrays consisting of integrated oscillator-antenna elements; and grid oscillators and their derivatives which are hybrids of the other two categories. This paper outlines a new procedure for the accurate design of active antenna arrays consisting of elements comprising of a microstrip dipole directly integrated with a transistor. The analysis of the dipole-transistor units models the structure completely and is able to treat the design of single elements, infinite arrays and finite arrays. It does not neglect the effect of key components of the structure such as inter-element interaction, edge effects of finite arrays and phenomena associated with the presence of the substrate.