Circumventing Bounds and Realizing Novel Performance Characteristics using Time-Varying Antenna Systems

#electromagnetic #Non-LTI #ESA #antenna #ChuLimit #RemoteSensing #communications

Fundamental physical limits apply to many key antenna performance parameters (gain, Q-factor, efficiency), particularly when device dimensions are small relative to operating wavelengths – the “electrically small” regime. These limitations cannot be exceeded by linear time-invariant (LTI) devices, and can manifest as critical bottlenecks for communications and sensing technology.

In this talk, we survey recent work on moving antenna technology away from the classical LTI design paradigm and toward active, non-linear, and time-varying systems. Emphasis is placed on research incorporating time-varying elements into antennas and matching networks with the goal 
of exceeding physical bounds on LTI antenna metrics. This includes direct antenna modulation (DAM), which treats time-varying antennas and matching networks as active parts of the modulation process, allowing for efficient, extreme instantaneous radiated signal bandwidths from 
electrically small apertures. Additionally, the co-design of electrically small antennas with parametric pumping networks for broadband, low-noise receive applications will be presented. 

Modeling challenges and simulation approaches for time-varying radiators will be discussed and several theoretical concepts in the area of time-varying antennas will also be surveyed, including the extension of effective aperture to time-varying antennas and the effect of cross-frequency coupling on the effective receiver noise temperature.