Kemp Mark A, Franzi Matt, Haase Andy, Jongewaard Erik, Whittaker Matthew T, Kirkpatrick Michael, Sparr Robert
SLAC National Accelerator Laboratory, 2575 Sand Hill Rd., Menlo Park, CA, 94025, USA.
Gooch and Housego, LLC., 676 Alpha Drive., Highland Heights, OH, 44143, USA.
Nat Commun. 2019 Apr 12;10(1):1715. doi: 10.1038/s41467-019-09680-2.
Very low frequency communication systems (3 kHz-30 kHz) enable applications not feasible at higher frequencies. However, the highest radiation efficiency antennas require size at the scale of the wavelength (here, >1 km), making portable transmitters extremely challenging. Facilitating transmitters at the 10 cm scale, we demonstrate an ultra-low loss lithium niobate piezoelectric electric dipole driven at acoustic resonance that radiates with greater than 300x higher efficiency compared to the previous state of the art at a comparable electrical size. A piezoelectric radiating element eliminates the need for large impedance matching networks as it self-resonates at the acoustic wavelength. Temporal modulation of this resonance demonstrates a device bandwidth greater than 83x beyond the conventional Bode-Fano limit, thus increasing the transmitter bitrate while still minimizing losses. These results will open new applications for portable, electrically small antennas.
甚低频通信系统（3千赫至30千赫）可实现一些在较高频率下不可行的应用。然而，辐射效率最高的天线需要达到波长尺度（在此处，大于1千米），这使得便携式发射机极具挑战性。为了实现10厘米尺度的发射机，我们展示了一种在声共振下驱动的超低损耗铌酸锂压电电偶极子，在可比的电尺寸下，其辐射效率比先前的技术水平高出300倍以上。压电辐射元件无需大型阻抗匹配网络，因为它在声波波长下自谐振。对这种共振进行时间调制，展示了一种超出传统博德-法诺极限83倍以上的设备带宽，从而在仍将损耗降至最低的同时提高了发射机比特率。这些结果将为便携式、电尺寸小的天线开辟新的应用领域。
