An X-band reflectarray, which consists of double square loop loaded by spiral stubs (DSL-SS) unit, is investigated in this communication. The DSL-SS unit is composed of a modified double square loop loaded by four spiral stubs and is analyzed by a simple circuit approach, which can analyze the complex multiple resonance structure and guide the design, to reveal its characteristic. The reflectarray is designed according to a detailed design procedure and is then fabricated on a single-layer FR-4 substrate, which covers an area of 192×192 mm 2 . The proposed reflectarray has a wider gain bandwidth and lower cross-polarization when compared with the conventional single-layer reflectarrays, and its measured gain, the aperture efficiency and 1-dB gain bandwidth are 24.4 dBi, 53.5% at the center 10 GHz, and about 38% (9.4~13.2 GHz), respectively. This new reflectarray antenna is especially useful for low-cost broadband communication applications.
Index Terms-Broadband antennas, reflectarray, resonance.0018-926X (c)
The advent of modern light-emitting diode (LED) techniques enables us to develop novel lighting systems with numerous previously unavailable features. Specifically, by using the fixtures for both illumination and to interrogate the space, source-to-sensor communication becomes possible at very low cost. In this paper, we present a novel framework to estimate the occupancy distribution in an indoor space using color-controllable LED fixtures (the same fixtures providing the illumination, simultaneously) and sparsely distributed non-imaging color sensors. By modulating randomly generated perturbation patterns onto the drive signals of the LED fixtures and measuring the changes in the color sensor responses, we are able to recover a light transport model for the room. Two approaches are proposed to estimate the spatial distribution of the occupancy, based on a light blockage model and a light reflection model, respectively. These two approaches, which can be combined, can faithfully reveal the occupancy scenario of the indoor space, while preserving the privacy of its occupants. An occupancy-sensitive lighting system can be designed based on this technique.
A novel wideband design of a Ka-band compact dual polarized horn is presented. In order to suppress multimode affection, a novel multimode conical horn replaces conical horn. The simulated 10dB return loss bandwidth is approximately 15.6% (ranging from 29.5 to 34.5GHz). The simulated insertion loss of the orthomode transducer is less than -0.15dB, the isolation less than -55dB, and the VS WR is less than 1.3 in the operating frequency (ranging from 31 to 33GHz). This structure has properties of not only a wide band, ultra-low insertion loss and high isolation, but also good impedance match, small size, and radiation pattern. A prototype has been manufactured and measured. S ince the simulated results are consisted with the measured ones, this novel compact structure has enormous potential for the dual polarized antenna.
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