Abstract We demonstrate a low-profile holographic imaging system at millimeter wavelengths based on an aperture composed of frequency-diverse metasurfaces. Utilizing measurements spatially-diverse field patterns, diffraction-limited images human-sized subjects are reconstructed. The is driven by single microwave source swept over band frequencies (17.5–26.5 GHz) and switched between collection transmit receive metasurface panels. High fidelity image reconstruction requires precise model for...

This article covers recent advances in the fusion of metasurface antenna design and computational imaging (CI) concepts for realization systems that are planar, fast, low cost. We start by explaining operation metamaterial antennas which can generate diverse radiation patterns. Their advantages distinctions from previous elucidated. then provide an intuitive overview CI framework argue a near ideal platform implementing such schemes at microwave frequencies. describe two implementations:...

We present a dynamic metamaterial aperture for use in computational imaging schemes at microwave frequencies. The consists of an array complementary, resonant elements patterned into the upper conductor microstrip line. Each element contains two diodes connected to external control circuit such that resonance can be damped by application bias voltage. Through applying different voltages circuit, select subsets switched on create unique radiation patterns illuminate scene. Spatial information...

We demonstrate a microwave imaging system that combines advances in metamaterial aperture design with emerging computational techniques. The flexibility inherent to guided-wave, complementary metamaterials enables the of planar antenna illuminates scene dramatically varying radiation patterns as function frequency. As frequency is swept over K-band (17.5–26.5 GHz), sequence pseudorandom interrogates scene. Measurements return signal versus are then acquired and reconstructed using methods....

We present a 3D computational imaging system based on mode-mixing cavity at microwave frequencies. The core component of this is an electrically large rectangular with one corner re-shaped to catalyze mode mixing, often called Sinai Billiard. front side the perforated grid periodic apertures that sample modes and project them into scene. radiated fields are scattered by scene measured low gain probe antennas. complex radiation patterns generated thus encode information onto set frequency...

Recently, a frequency-diverse, metamaterial-based aperture has been introduced in the context of microwave and millimeter wave imaging. The generic form is that parallel plate waveguide, which complementary metamaterial elements patterned into upper couple energy from waveguide mode to scene. To reliably predict imaging performance such an prior fabrication experiments, it necessary have accurate forward model predicts radiation aperture, for scattering arbitrary target scene, set image...

The resolution of a frequency diverse compressive metamaterial aperture imager is investigated. consists parallel plate waveguide, in which an array complementary, resonant elements patterned into one the plates. Microwaves injected waveguide leak out through elements, forming spatially waveform at scene. As scanned, waveforms change, such that scene information can be encoded onto set measurements. nature enables image reconstruction from significantly reduced number We characterize this...

We investigate the imaging capabilities of a one-dimensional, dynamic, metamaterial aperture that operates at lower part K-band microwave frequencies (17.5–21.1 GHz). The dynamic consists microstrip transmission line with an array radiating, complementary, subwavelength irises patterned into upper conductor. Diodes integrated resonators provide voltage-controlled switching resonant elements between radiating and nonradiating states. Applying series on/off patterns to produces distinct...

When coupled to a tuning mechanism, disordered medium provides powerful means for shaping electromagnetic waveforms. The authors leverage this functionality conduct volumetric computational imaging: A deformed cavity is outfitted with tailored, irregular surfaces, and its microwave resonant modes are projected into an imaging domain retrieve the scene's spatial information. This approach could be applied biomedical imaging, security screening, or wireless power transfer telecommunications.

We demonstrate a frequency diverse, multistatic microwave imaging system based on set of transmit and receive, radiating, planar cavity apertures.The cavities consist double-sided, copper-clad circuit boards, with series circular radiating irises patterned into the upper conducting plate.The iris arrangement is such that for any given transmitting receiving aperture pair, Mills-Cross pattern formed from overlapped patterns.The distribution provides optimum coverage scene in spatial Fourier...

We demonstrate a frequency-diverse aperture for microwave imaging based on planar cavity at K-band frequencies (18-26.5 GHz). The structure consists of an array radiating circular irises patterned into the front surface double-sided printed circuit board. are distributed in Fibonacci pattern to maximize spatial diversity scene. is phase-diverse system and encodes imaged scene information onto set that span K-band. Similar recently reported metamaterial apertures, imager does not require any...

Abstract Mobile devices, climate science, and autonomous vehicles all require advanced microwave antennas for imaging, radar, wireless communications. We propose a waveguide-fed metasurface antenna architecture that enables electronic beamsteering from lightweight circuit board with varactor-tuned elements. Our approach uses unique feed structure layout spatial sampling at the Nyquist limit of half wavelength. detail design this experimentally demonstrate in two directions. can realize high...

We present numerical simulations of the near-field focusing capabilities a dynamically reconfigurable holographic metasurface aperture. The aperture consists parallel-plate waveguide in which upper plate is patterned with number metamaterial irises that can be switched between radiating ( <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> ) and non-radiating xmlns:xlink="http://www.w3.org/1999/xlink">OFF</sub> states. A cylindrically...

Radio imaging devices and synthetic aperture radar typically use either mechanical scanning or phased arrays to illuminate a target with spatially varying radiation patterns. Mechanical is unsuitable for many high-speed applications, contain active components are technologically cost prohibitive at millimeter terahertz frequencies. We show that antennas deliberately designed produce different patterns as the frequency varied can reduce number of necessary while still capturing high-quality...

We present the design and simulation of a frequency-diverse aperture for imaging human-size targets at microwave wavelengths. Predominantly relying on frequency sweep to produce diverse radiation patterns, provides path all-electronic operation, sampling scene without requirement mechanical scanning or expensive active components. Similar other computational schemes, removes many hardware constraints by placing an increased burden processing analysis. While proof-of-concept simulations...

Conventional microwave imaging schemes, enabled by the ubiquity of coherent sources and detectors, have traditionally relied on frequency bandwidth to retrieve range information, while using mechanical or electronic beamsteering obtain cross-range information. This approach has resulted in complex expensive hardware when extended large-scale systems requiring ultrawide bandwidth. Relying can create difficulties calibration, alignment, dispersive objects. We present an alternative...

A medium that exhibits artificial magnetism can be formed by assembling an array of split ring resonators (SRRs)—planar conducting elements exhibit a resonant response to electromagnetic radiation. The SRR large magnetic dipole moment when excited field directed along its axis. However, the also electric quite depending on symmetry and orientation with respect component field. So, while considered as having predominantly for certain orientations incident wave, it is generally case...

We present angle-resolved free-space transmission and reflection measurements of a surface composed complementary electric inductive-capacitive (CELC) resonators. By measuring the coefficients CELC with different polarizations particle orientations, we show that only responds to in-plane magnetic fields. This confirms Babinet duality between its complement, field coupled LC resonator. Characterization structure serves expand current library resonant elements metamaterial designers can draw...

A frequency‐diverse computational imaging system synthesised using three‐dimensional (3D) printed metasurface antennas is demonstrated. The 3D fabrication of the achieved a combination polylactic acid (PLA) polymer material and conductive (Electrifi), circumventing requirement for expensive time‐consuming conventional techniques, such as machine milling, photolithography, laser‐etching. Using antennas, composite aperture designed simulated in K‐band frequency regime (17.5–26.5 GHz). capable...

The authors present a multistatic imaging system at microwave frequencies based on arrays of planar cavity sub‐apertures, or panels. imager consists sets transmit and receive panels, loaded with radiating irises distributed over the sub‐apertures in an aperiodic pattern. This frequency‐diverse aperture produces distinct radiation patterns as function frequency that encode scene information onto set measurements; images are subsequently reconstructed using computational approaches. Similar to...

Emerging metasurface antenna technology enables flexible and low cost massive multiple-input multiple-output (MIMO) millimeter-wave (mmW) imaging for applications such as personnel screening, weapon detection, reconnaissance, remote sensing. This work proposes an orthogonal coded active illumination (OCAI) approach which utilizes simultaneous, mutually transmit signals to illuminate the scene being imaged. It is shown that OCAI robust code amplitude phase imbalance introduced by imperfect...

We study the surface plasmons (SPs) that exist at interface between air and a metamaterial constructed of split ring resonators (SRRs). The SRR possesses frequency band in microwave regime $(12.5--14\phantom{\rule{0.3em}{0ex}}\mathrm{GHz})$ over which permeability is negative. apply an attenuated total reflection technique Otto configuration beam microwaves reflected from higher dielectric (polycarbonate) prism to excite probe plasmons. resulting evanescent fields on transmission side couple...

We derive simple analytical expressions to model the electromagnetic response of an electrically large printed cavity. The is then used develop cavities for microwave imaging purposes. proposed cavity excited by a cylindrical source and has boundaries formed subwavelength metallic cylinders (vias) placed at distances apart. Given their small size, electric currents induced on vias are assumed have no angular dependence. Applying this approximation simplifies problem matrix equation which can...

We investigate the effects of disorder on metamaterial samples composed split ring resonators with randomly introduced variation in their geometrical dimensions. demonstrate that broadens negative permeability band and introduces effective losses into system. Transmission measurements varying degrees are found to be excellent agreement predictions based standard homogenization theories.

Computational imaging systems leverage generalized measurements to produce high-fidelity images, enabling novel and often lower cost hardware platforms at the expense of increased processing. However, obtaining full resolution images across a large field-of-view (FOV) can lead slow reconstruction times, limiting system performance where faster frame rates are desired. In many scenarios, highest is needed only in smaller subdomains interest within scene, suggesting an aperture supporting...