engleski

Suppression of undesired operating modes of a push-pull active integrated antenna

The paper considers a new design of an active patch antenna with integrated push-pull oscillator. The patch was fed at two points with signals having 180° phase shift in order to excite the desired mode. Since a system of two active elements may operate in odd and even modes on the design frequency and its harmonics, the undesired modes have to be suppressed. This was obtained by controlling the negative resistance at the oscillator outputs and the coupling between the active elements. Further suppression has been obtained by symmetrical design of the active antenna. An active rectangular patch antenna with push-pull oscillator, embedded inside a rectangular opening in the patch, has been manufactured. The theoretical results have been compared with measurements. The antenna showed stable operation and clean spectrum. The radiation patterns of the patch were not affected by the modifications and by the oscillator circuit. External injection locking of this active antenna was successfully demonstrated.

active antennas; microstrip antennas; oscillators; spatial power combining

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