Antenna bandwidth engineering through time-varying resistance

Abstract

The operational bandwidth of resonant circuits is limited by the resonator's size, which is known as the Chu limit. This limit restricts miniaturization of antennas, as the antenna bandwidth is inversely proportional to its size. Here, we propose slow time modulation of resistive elements to engineer bandwidth of small antennas. The temporal modulation of resistance induces virtual impedance that is fully controlled by the modulation parameters. We show how the virtual impedance can be used to optimize the frequency response of a resonant circuit, leading to enhanced matching at multiple frequencies simultaneously. We experimentally verify the proposed technique, demonstrating enhancement of radiation of a broadband modulated signal radiated by a small antenna.

APL special topic: Time modulated metamaterials

“…Several applications are also suggested in this Special Issue, such as switching the transmission response of THz wave, 23 secure wireless communication, 24 engineering bandwidth of small antennas, 25 and controlling the radiation of the nonlinear waves. 26…”

Time-Modulated Circuits and Metasurfaces for Emulating Arbitrary Transfer Functions

“…For instance, one can design efficient systems that realize unconventional functionalities [2][3][4][5][6][7]. In addition to that, many conventional limitations imposed on static systems can be overcome using time modulations [8], for instance, enhancing radiation from electrically small antennas beyond the Chu limit [9][10][11], breaking timereversal symmetry and achieving magnetless nonreciprocity [12][13][14][15][16][17][18][19], accumulation of energy with reactive elements [20], versatile absorption control [21], and more [22,23].…”