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In this letter, we propose and experimentally demonstrate a space‐fed beamforming approach capable of steering beams up to ±70° with a focal ratio (F/D) reduced to 0.27 and a scan loss remained 4 dB. It is implemented based on an mmWave phase reconfigurable metasurface, and an unconventional array‐fed architecture. By doing so, while the total profile of conventional space‐fed phased arrays can be significantly reduced, specifications such as scan range and scan loss can be simultaneously improved. Compared with conventional phased array systems, such specifications are unique, and can be used to realize low‐profile, cost‐effective, space‐fed phased arrays requiring ultrawide coverages at mmWave frequencies. [ABSTRACT FROM AUTHOR]

We investigate a non-Foster element implemented with a radio-frequency operational amplifier theoretically and experimentally, showing that its full-range frequency response exhibits an inverted Lorentzian resonance, and thus a high-frequency non-Foster response can be observed on the right side of the resonance region. This can be used to overcome the technical difficulty in achieving high-frequency non-Foster elements. [ABSTRACT FROM AUTHOR]

In this article, we propose a design and on-board measuring approach for the realization of micro-sized differential antennas for the 2.4-GHz mobile payment (MP) applications. Exampled by a complete realization of a 3 × 11 mm-sized differential antenna driven by a commercial 2.4-GHz transceiver integrated inside a 15 × 11 mm-sized micro-SD card, such design and testing approach is described in detail. The experimental measurements of the micro-sized antenna show that the impedance of the designed micro-sized differential antenna well matches the complex impedance of the transceiver, and, therefore, ensure the stability of the radio frequency performance required by the MP applications. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1419-1422, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25957 [ABSTRACT FROM AUTHOR]