Frequency-modulated continuous waves controlled by the hidden surface of space-time encoding with non-linear periodic phases

Under the control of a field-programmable gate array (FPGA) that introduces external non-linear cyclic voltage control signals, different types of FMCW signals can be synthesized as required in the same STCM platform. By optimizing the initial voltage distributions between different regions of the superficial surface, the propagation directions of FMCW beams can be freely manipulated. Credit: Jun Chen Ke et al

Pulse compression is an important technology in modern radar systems and promotes the development of modern radar technologies towards higher speed and accuracy. Modified frequency continuous wave (FMCW) signals, with the advantages of large time width and large bandwidth, have become the typical pulse compression signals.

However, FMCW signals are generated primarily by voltage-controlled oscillators (VCOs) or direct digital synthesis (DDS) techniques, causing significant system complexity and difficulty in integration with antenna modules. Therefore, one of the important questions for researchers is how to design a low-cost and high-efficiency method for FMCW signal generation.

In a new paper published in Light: science and applicationsA team of scientists led by Professors Qiang Cheng and Tie Jun Cui from the State Key Laboratory for Millimeter Waves and the Institute of Electromagnetic Space, Southeast China University, and their co-workers have developed a Theoretical framework and a method for simultaneously generating FMCWs and controlling spatial propagation behaviors via a novel STCM with non-linear periodic phases.

The research team designed a reflection-type STCM with full 360-degree stage coverage. When biased by the voltage nonlinear periodic control signals, the nonlinear periodic phase responses can be acquired and modulated to the incident electromagnetic (EM) waves instantly. In this way, FMCW signals with instantaneous, time-varying frequencies can be synthesized.

The time-frequency characteristics of the STCM-based FMCW signals are closely related to the nonlinear periodic voltage control signals. By programming control signals, different types of FMCW signals can be manufactured on the same STCM upon request.

In addition, by optimizing the initial voltage distributions between different regions of the supersurface, additional phase gradients can be introduced into the hidden surface, and then propagation directions of the FMCW beams can be manipulated. The reported method will lay the foundation for new signal pulse compression techniques. Scientists summarize the operating principle of this work:

“We design a method to simultaneously generate FMCWs and control their spatial propagation behaviors for two purposes in one: (1) to synthesize FMCW signals by designing required nonlinear cyclic voltage control signals; and (2) to manipulate FMCW beam propagation directions by optimizing initial Voltage Distributions between different regions of the metasurface. “

“Compared with the traditional method of FMCW signal generation, the proposed method does not need frequency tuning and phased array antenna modules, which can effectively reduce cost and complexity,” the scientists say.


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more information:
Jun Chen Ke et al, Frequency modulated continuous waves controlled by hidden surface encoding spacetime with nonlinear periodic phases, Light: science and applications (2022). DOI: 10.1038/s41377-022-00973-8

the quote: Frequency Modulated Continuous Waves Controlled by Hidden Surface Encoding Spacetime with Nonlinear Periodic Phases (2022, September 15) Retrieved September 15, 2022 from

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