Demonstration of Simple Electronic Near-Field Beamforming Using Multitone Microwave Signals With a Leaky-Wave Focused Applicator

A simple technique to electronically shape the power distribution of a microwave focused beam in the near-field range is proposed and experimentally demonstrated in this letter. This technique is based on the use of a multitone microwave input signal that is spatially scattered due to the frequency-scanning response of a leaky-wave focused applicator. A synthesis procedure based on the minimax algorithm is applied to optimize the frequencies and power amplitudes of the multitone signal. Experiments using multitone signals in the [14-16 GHz] band and a microstrip leaky-wave line are reported, showing the ability to dynamically shape the near-field focus, steering its position over a range of 55 mm, controlling the focal depth from 28 to 87 mm, and showing electronic generation of multifocused spots with complementary power distributions .