Journal of Applied Physics,
Год журнала:
2024,
Номер
136(19)
Опубликована: Ноя. 21, 2024
This
paper
unveils
a
pioneering
ultra-wideband
metasurface,
achieving
both
optical
transparency
and
significantly
reduced
scattering,
surpassing
current
stealth
material
limitations.
A
novel
dual-layer
meta-atom,
expertly
balanced
for
polarization
conversion
absorption,
is
meticulously
fine-tuned
through
equivalent
circuit
analysis
sophisticated
genetic
algorithm,
targeting
broad
operational
bandwidth.
By
ingeniously
arranging
these
meta-atoms
alongside
their
mirrored
twins,
we
facilitate
an
efficient
redistribution
of
scattered
cross-polarized
energy,
leading
to
substantial
reductions
in
radar
detectability.
Simulation
validations
experimental
results
affirm
marked
improvement
performance,
characterized
by
co-polarized
RCS
reduction
excess
10
dB
across
the
extensive
3.7–25.9
GHz
band.
groundbreaking
metasurface
offers
versatile
solution
wideband
electromagnetic
control
aerospace,
telecommunications,
applications,
pushing
boundaries
technology.
Polymer Composites,
Год журнала:
2024,
Номер
unknown
Опубликована: Авг. 13, 2024
Abstract
Epsilon‐negative
materials
(ENM)
at
radio
frequency,
usually
designed
based
on
percolation
theory,
recently
drew
much
attention
because
of
their
potential
applications
in
capacitors,
transistors,
and
antennas.
However,
randomly
distributed
conductive
functional
cannot
achieve
directional
long‐range
electron
transportation
within
the
material,
resulting
decreased
utilization
efficiency.
The
morphology
design
substrate
material
can
change
distribution
state
transfer
pathway
fillers.
By
controlling
size
polystyrene
(PS)
content
multi‐walled
carbon
nanotubes
(MWCNTs),
PS/MWCNTs
composites
with
random
structures
segregated
were
designed,
both
which
exhibited
negative
permittivity
increasing
MWCNTs
content.
Further
investigation
revealed
that
behavior
is
due
to
establishment
network
plasma
oscillation
free
electrons.
Moreover,
components
have
lower
thresholds,
as
transport
achieved
fillers
are
efficiently
utilized.
This
work
provides
a
new
method
for
guiding
effectively
changing
ENM.
Highlights
Negative
by
frequency.
structure
leads
decrease
threshold.
good
prospects
inductive
components.
Underwater
ultrasonic
detection
is
critical
for
marine
security,
playing
a
vital
role
in
resource
development,
environmental
protection,
and
national
defense.
However,
existing
systems,
which
primarily
rely
on
active
scanning
technologies,
are
hindered
by
high
costs,
significant
energy
demands,
challenges
achieving
large-scale
deployment.
Here,
we
introduce
microfiber-based
triboelectric
acoustic
sensor
(MTAS)
featuring
core-shell
hierarchical
structure,
offering
self-powered
solution
precise
measurement
of
underwater
ultrasound
source
distance.
By
leveraging
the
principles
contact
electrification/triboelectrification
electrostatic
induction,
MTAS
efficiently
converts
complex
vibrations
into
real-time
electrical
signals.
The
demonstrates
rapid
response
times
as
low
8.6
μs,
signal-to-noise
ratio
29.8
dB,
capability
to
detect
sources
with
power
levels
above
1.6
W
via
time-difference-of-arrival
analysis.
To
address
sea
applications,
further
propose
distributed
network
that
integrates
multiple
units
capable
localization
motion
trajectory
visualization.
This
innovation
represents
transformative
approach,
combining
operation,
ease
deployment,
imperceptibility,
paving
way
large-area,
energy-efficient
submarine
security
systems.
Such
advancements
redefine
paradigm
target
detection,
aligning
technological
pressing
demands
safety
sustainability.
Metals
have
traditionally
served
as
the
primary
functional
phase
in
development
of
metamaterials
exhibiting
epsilon-near-zero
(ENZ)
and
epsilon-negative
(EN)
responses,
albeit
with
persisting
ambiguities
regarding
their
response
mechanisms.
This
paper
presents
tunable
ENZ
(ε'
~
0)
EN
<
parameters
at
20-MHz
to
1-GHz
region
based
on
Cu/CaCu3Ti4O12
(Cu/CCTO)
metacomposites.
By
means
first-principles
calculations
multi-physics
simulations,
underlying
mechanisms
governing
responses
are
unveiled.
The
intricate
pathways
through
which
metacomposites
achieve
2
dielectric
delineated:
At
low
Cu
content,
a
weak
(|ε'|
200)
was
excited
by
electric
dipole
resonance,
accompanied
effect;
conversely,
high
due
increase
effective
electron
concentration,
plasmonic
oscillation
behavior
occurs
constructed
3-dimensional
network,
resulting
strong
1,000)
radio
frequency
band.
These
phenomena
explicated
distinct
Cu/CCTO
models:
an
isolated
state
connected
network
state.
study
not
only
comprehensively
elucidates
achieved
typical
metals
phases
but
also
delves
into
associated
electromagnetic
shielding
thermal
properties,
providing
theoretical
basis
for
practical
applications.
