Optimum design of feed structures for high G/T passive and active antenna arrays

Abstract

In this work, noise analysis of parallel feed structures is presented. Signal and noise behavior of the feed structures are signified by the newly introduced concepts of "coherent" and "incoherent" impedance match of power-combining structures. It is also shown that a feed structure can be redesigned for lownoise operation without affecting the radiation characteristics. Optimum design of parallel feed structures for low-noise operation is explained. Also an optimum use of active elements in such structures is investigated to have a low overall noise temperature of the antenna array with minimum number of active elements. In the analysis, a new method is introduced where a "noiseequivalent line length" (NELL) is defined. This definition, which unifies the contribution of noise from different array elements, is used in the design of a parallel feed structure and as an active circuit replacement criteria in passive arrays.

A review on array mutual coupling analysis

“…Those mainly come from the environment (like noise radiated by the warm ground, which needs to be carefully avoided for radio astronomy applications), from the front‐end amplifiers and from the losses that may occur on the antennas themselves. While several seminal papers provide signal‐to‐noise (or, equivalently, gain‐over‐noise temperature) ratios for multiple‐antenna systems [ Demir and Toker , 1999; Kraft , 2000], several more recent studies analyze more specifically the effects of mutual coupling on the noise performance of arrays. In this section, we analyze the effects of mutual coupling on the noise budget of such arrays.…”

Noise in the Presence of Coupling Among Antenna Elements

“…For the case where there is no reflected power from the antenna tenninals of the feed structe, noise power at the output port is obtained using its noise equivalent line length as described in Denir and Toker (1). Therefore, Poutl can be calculated by this way.…”

Communication link improvement through antenna optimization for satellite, space, and radio astronomy systems

“…Reflector antennas have limited reconfigurability, hence limited potential for improvement in the link quality. A more substantial improvement can be obtained for array antennas, where the feed structure offers more degrees of freedom in the pattern optimization process [3].…”