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A novel configuration of a metasurface unit cell is proposed to independently control its reflection phase and magnitude at the specified frequency and is demonstrated using an equivalent circuit model. The unit cell of the proposed metasurface structure consists of two resonators with integrated resistive and capacitive loads in each resonator, which are respectively responsible for dynamically controlling the reflection magnitude and phase. An equivalent circuit model of such confirmation is developed to study the reflection response of the metasurface as a function of various lumped-element controls. It is shown that an arbitrary combination reflection amplitude and phase can be achieved by appropriate combination of these lumped elements. Using commonly available tunable resistive and capacitive components, a real-time tunable metasurface is envisioned where the reflection amplitude and phase of the metasurface can be engineered with complete flexibility.

A simple stacked dielectric structure is presented to achieve a broadband filtering response at millimeter-wave (mm-wave) frequencies. The structure consists of alternative slabs of different dielectric materials (non-periodic designs possible) to exhibit a bandpass response. The structure is designed using a transmission line model and confirmed with full-wave simulations. Compared to standard printed circuit board (PCB) fabrication, stacked dielectric structures are expected to exhibit better loss performance, due to absence of metallic patterns, and be easier to fabricate at mm-waves because of the absence of constraints from PCB line-width/gap dimension tolerances. An example structure was designed, fabricated, and measured with a center frequency 57 GHz consisting of three dielectric slabs and two air gaps. ANSYS FEM-HFSS simulations of this structure show well-matched bandpass performance, insertion loss of less than 1 dB, and a 3-dB bandwidth of 4.5 GHz. Measurement of the fabricated structure shows excellent performance and correlation with simulation.

This paper presents a general formulation for determining the scattered Electromagnetic fields present for a multi-surface configuration of curvilinear interfaces comprised of metasurfaces, dielectrics and perfect conductors. The method uses a Boundary Element Method (BEM) formulation of the frequency domain version of Maxwell’s equations, where the general metasurface boundaries are represented in terms of surface susceptibilities which are then integrated within the BEM using the Generalized Sheet Transition Conditions (GSTCs). These curvilinear surfaces are next described by parametric equations allowing for an elegant formulation for geometrically complex systems. The proposed method is then demonstrated using a numerical example.

A novel all-dielectric Huygens’ metasurface pair capable of circularly-polarized beam-forming is proposed. The proposed structure consists of two layers of dielectric resonators separated by approximately one quarter-wavelength at the design frequency. Each dielectric resonator is symmetrical to allow for the transmission of circularly-polarized waves. In order to physically design the structure, each resonator is connected to neighboring resonators using four symmetrical bridges. The second dielectric layer is added to cancel reflections caused by the bridges, allowing for the achievement of perfect matching. Fullwave simulations are used to demonstrate the full phase range achieved by varying unit cell dimensions. The operation of the proposed metasurface is further demonstrated by obtaining refracted and difference-pattern beams from a circularly-polarized slot array antenna.

This paper presents a rigorous mathematical map- ping between the complex eigenmodes and the complex propagation constant for a homogeneous lossy waveguide structure. We validate the results for a rectangular waveguide, comparing the analytical mapping with the results from a FEM-EM solver. It has been found that a precise mapping between Ω(β) and γ(Ω) exists, which enables predicting the driven mode solution from the eigenmode analysis. While valid for a simple canonical case of a dispersive waveguide, such mapping establishes the underlying principles of how the complex eigenmodes are formulated inside typical commercial simulators.

Space-modulated diffraction gratings are modelled and analyzed using a zero thickness metasurface grating approach, and demonstrated using numerical examples. The constitutive parameters of the grating are described using surface susceptibilities of the Lorentzian form, where their resonant frequencies are sinusoidally modulated. They are then solved self-consistently with the Generalized Sheet Transition Conditions (GSTCs) to determine the scattered fields from the metasurface for specified plane-wave incident fields, for various cases of modulation periodicities and depths.

A novel analog and real-time spectral decomposition system for signal processing at millimeter-wave (mmwave) frequencies is proposed and demonstrated using full-wave simulations. The system is based on a multi-port leaky-wave antennas (LWAs) structure formed using an array of $N 1-D$ LWAs with $2 N$ ports. When this structure receives a broadband time-domain signal from a single direction, the signal’s various spectral components are separated in real-time. They subsequently appear at the various ports of the LWAs following their respective beam-scanning laws. The proposed concept is demonstrated using frequency and time-domain full-wave simulations of two slot array antennas to decompose a transient pulse into four frequencies. The frequency outputs are then correlated back to the beam-scanning laws of the antennas.