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A dual polarized high gain dielectric lens antenna with frequency agility from 20.8 GHz to 25.4 GHz is proposed. A plano-convex dielectric lens is used to focus the beam from the patch antenna in the forward direction resulting in higher realized gain. Co-pol and cross-pol separation of 15 dB for both polarizations is reported in the forward direction. In this antenna design, variable capacitors are...
A reconfigurable fractal-shaped slot-ring antenna with wide bandwidth is presented. The antenna is able to switch between two modes using 8 PIN diode switches. In the first mode, the proposed antenna operates at S band with 70% fractional bandwidth (FBW). In the second mode of operation, the antenna covers C band with 67% FBW. Fractal shapes are incorporated into the antenna structure to significantly...
In this paper, a concept of a compact reconfigurable quarter-wave patch antenna employing a folded loading stub and a tuning varactor is presented. The structure consists of two substrate layers separated by a ground plane. The antenna is placed on the top metal layer whilst the entire feeding structure and the bias circuit are located on the bottom layer. The central result of the paper is the folded...
A frequency-reconfigurable wideband antenna with dual-notch response for cognitive radios (CRs) application is presented. By placing stub-loaded resonators beside the feed line, two notched bands are generated. The central frequency of one notched band can be controlled by loading varactors while the other notched band remains constant. The biasing circuits for the varactors consist of Bias T and...
In this paper a new evolutionary optimization algorithm will be introduced: Leadership Based Optimization (LBO). This algorithm will be tested on some mathematical benchmark functions and on the optimization of the array factor of a planar reflectarray antenna.
A 60 GHz substrate integrated waveguide (SIW)-based Vivaldi antenna with low cross-polarization and side lobe levels is presented. The feed system is implemented using microstrip-to-SIW transition, SIW, and SIW-to-slot-line transition. The simulated and measured results show a nearly flat gain of 15 ±0.4 dB over the frequency range of 55–65 GHz. In addition, a good impedance matching and symmetric...
A millimeter wave antenna array with polarization flexibility and wide-angle azimuth phase scan is presented. The antenna structure consists of a stripline feeding network that excites a linear array of rectangular cavities through coupling slots. The radiating slots, placed on the top of the cavities, can be oriented in any direction to realize the desired polarization. A linear array is designed...
The architecture of a 94-GHz quasi-circulator is proposed using a hybrid coupler, directional phase shifters, and a Wilkinson power divider. Different designs for the DPS are analyzed to obtain good performance. Block-level simulations are conducted to verify the operation of the proposed architecture. Good isolation between transmitter and receiver ports are demonstrated.
Complementary-split-ring (CSR) Slotted Waveguide Antennas have been proven to be critical to high-power-microwave (HPM) systems, due to their compact size, high gain and high power-handling capability. CSR-SWA designs depend on highly accurate electromagnetic simulations that take geometric details into full account. Conventional antenna manufacturing approaches such as direct machining and platelet...
This paper proposes a propagation path identification method by combining Finite-Difference Time-Domain (FDTD) method and compressive sensing. By regarding a number of Yee cells as a plane array antenna, compressive sensing can be applied to estimate the direction-of-arrival (DOA) of the radio wave in FDTD method. In this method, the signal is transmitted backward and forward between two TRx antennas,...
This work presents a numerical method for modeling electromagnetic scattering from two-dimensional cavities embedded in a perfectly conducting ground plane. First, the problem is discretized in time with Newmark's method, then solved using finite-element boundary-integral technique. A proof is presented to demonstrate that the discretized variational formulation is well-posed at each time step.
We present a full-wave, finite-element time-domain (FETD)-based electromagnetic particle-in-cell (PIC) algorithm for unstructured grids with explicit field update. Charge conservation is attained from first principles by utilizing scatter and gather steps based on the representation of fields, currents, and charges by differential forms of various degrees. A sparse approximation inverse (SPAI) is...
An inverse Doppler shift occurs in a photonic crystal (PC) bounded by a moving wall. The interpretation of this result has stirred some controversy. In this paper, we address the problem using a diagrammatic approach. This visual representation provides immediate insight into the phenomenon, and is a powerful tool for the design of time-varying PCs.
The environmental impact, the toxicity, and the high cost of agrochemicals adopted in intensive agriculture are stimulating the study of innovative solutions for the management of the phytosanitary treatments. The proposed wireless monitoring system aims at reducing the level of the pesticides while ensuring a high quality production. A wireless sensor network is designed for the local measurement...
This paper presents the wireless measurement of the incident pressure inside the fire ball of an air blast shock wave. The wireless sensor set-up and the experimental configuration are described. The wired and wireless experimental results are compared and analyzed. To our best knowledge, it is the first time that a wireless device takes place inside the fireball of an explosion for the measurement...
A thin high gain switched beam (0°, 25° and 335°) parasitic antenna array is presented. Using a non-uniform aperiodic EBG array thickness of 0.04 wavelength and 8.4 dBi peak gain is achieved. The Forward-to-Back ratio (F/B) is as high as 30 dB.
Ground-based and shipborne Communications ESM systems operating in the VHF and UHF bands have been typically based on arrays designed accordingly to regular geometries. Prominent example are Uniform Circular Arrays (UCAs). Unfortunately, UCAs are not easily installable on small or narrow platforms, as it is in the case of UAVs; this is due also to the long wavelengths of the signals in the VHF band...
In this paper, a compact center-fed reconfigurable CP Archimedean spiral antenna, capable of generating two orthogonal CP waves, is presented. Dual circular-polarization performance of the four-arm antenna is investigated in terms of its flare rate variation. It is shown as spiral flare rate varies from 2mm/rad to 3mm/rad the high-end frequency considerably increases and dual-polarization performance...
In this contribution we evaluate a direction finding system based on two planar spiral antennas mounted in a squinted fashion and using amplitude information only. This concept avoids hybrids for beam formers or summation networks which makes the antenna elements the only bandwidth-limiting components. With a 10-turn spiral a 1:36 bandwidth and a field of view of 157° is theoretically demonstrated.
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