  This article revisits integrated sensing and communication (ISAC) systems
that operate in the near-field region of large antenna arrays while utilizing
large bandwidths. The article first describes the basic characteristics of a
wideband sensing and communication (S&C) channel, highlighting the key changes
that occur during the transition from the far-field to the near-field region,
namely strong angular delay correlations and non-uniform Doppler frequencies.
It is then revealed that the near-field effect can facilitate wideband-like S&C
functionality, leading to efficient signal multiplexing and accurate distance
sensing, and making large antenna arrays a viable alternative to large
bandwidths. In addition, new capabilities for Doppler-domain signal
multiplexing and velocity sensing enabled by non-uniform Doppler frequencies,
which cannot be achieved by extending the bandwidth alone, are presented.
Motivated by these results, several paradigm shifts required to leverage the
full potential of near-field wideband ISAC systems are discussed, with
particular emphasis on spectrum allocation, antenna array arrangement,
transceiver architecture, and waveform design.
