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This paper presents an overview of the advances in single layer reflectarrays. In particular, it reports the progress in wideband reflectarrays and reconfigurable reflectarrays.
Wireless energy harvesting (WEH) from ambient electromagnetic fields is becoming an emerging technology that can be exploited as a power source for many low power electronic devices. A number of key challenges are identified but the optimum design of rectennas for ambient WEH is very challenging. This paper presents a review on recent progress in multiband and broadband rectennas for WEH and wireless...
A broadband metasurface Luneburg lens based on glide-symmetric bed of nails is designed. First, the Luneburg lens was re-shaped using quasi-conformal transformation optics. With this technique, the original circular focal curve of the lens is changed to a straight line. Afterwards, the refractive index distribution of the optically transformed lens is realized by changing the height of the pins in...
For integration into flat mounting volumes in cars a new wideband antenna is presented covering all frequency bands for cell phone LTE and 5G starting with the LTE low band at 698 MHz up to the WLAN frequency bands at 6 GHz. The performance of the antenna as a single part is shown by way of measurement and simulation and a pair of antennas is measured in a car on a turntable regarding its mutual coupling...
We present two configurations of multiport antennas for Multiple-input Multiple-output (MIMO) application. The configurations are comprised of three and four dual-polarized self-grounded bowtie antenna as the element, respectively. The MIMO performance of both antennas is evaluated in Random Line-of-Sight (Random-LOS) and Rich Isotropic Multipath (RIMP) channel models as two edge propagation environments...
This paper presents recent developments in metaline-based antennas. Four metalines are presented and application of these metalines to low-profile antennas is discussed: (A) zeroth-order metaline antenna, (B) double metaline antennas, (C) metaloop antennas, (D) metaspiral antennas, and (E) metahelical antennas. Wideband broadside radiation from double metaline antennas and dual-band counter circularly-polarized...
The design of circular dual and quad ridged horn antennas covering the 18 to 45 GHz band is discussed. An exponential taper and blending fillet for the ridge profile are presented to minimize 3 dB beamwidth variation while maintaining high boresight gain for both dual and quad ridge horns. Boresight gain for a quad ridge design is greater than 15 dBi, while boresight gain greater than 17.9 dBi is...
Silicon optics with broadband antireflective (AR) treatments are being developed for millimeter and submillimeter-wave applications. Combined photolithography and deep reactive ion etching (DRIE) techniques are used to texture the surfaces of high resistivity, low loss silicon wafers. We report on the design, fabrication, and testing at 250 GHz of single and double layer AR treatments on silicon optics.
Recently, the concept of partially reflecting surface (PRS) with positive reflection phase gradients has been proposed for the design of wideband cavity antennas. In this work, we numerically and experimentally implemented this idea and demonstrated a broadband and highly directive Fabry-Pérot cavity antenna (FPCA) with dual layer PRS at microwaves. Good performance of impedance matching bandwidth...
A wideband mechanical beam steering lens antenna was proposed in this paper. Referring to the operating principle of Risley beam steering system, a fixed beam array antenna was utilized to excite the dielectric wedge lens at Ku-band. By controlling the relative rotation between the feed and the lens, the whole antenna system can scan to ±50° in all directions. The whole profile was integrated to minimum...
A four-layer square split-rings frequency selective surface is applied for designing a polarization converter. The new proposed polarizer operates in broadband, from 6.4 to 13.7GHz, which can generate circularly polarization waves from incident linearly ones at 45° title incidence to the structure. The new polarization converter is optimized and fabricated. Experimental results show that the polarizer...
This paper presents results of an investigation carried out on the large directivity bandwidth of a multi-layer all-dielectric resonant cavity antenna (RCA). This RCA comprises of a multi-layer all-dielectric superstructure, which exhibits a measured broadside directivity of 18.1 dBi with an extremely large 3-dB directivity bandwidth of 51%. Unit cell model of the superstructure is studied by employing...
This work presents a spiral antenna array, which can be used in the V- and W-Band. An array equipped with Dolph-Chebychev coefficients is investigated to address issues related to the low gain and side lobe level of the radiating structure. The challenges encountered in this achievement are to provide an antenna that is not only good matched but also presents an appreciable effective bandwidth at...
We investigate two novel microstrip-line antennas. They are composed of symmetric and asymmetric dual-loop radiation elements, respectively. Based on the radiation characteristics of the symmetric (reference) antenna, the asymmetric (present) antenna is designed using the method of moments. It is found that the present antenna radiates a circularly polarized wave with an axial ratio of less than 3...
Transpolarizing surfaces rotate by 90-degree the polarization of the reflected wave with respect to the incident one. A novel transpolarizing or crosspolarizing surface has been proposed. Two different geometries (for broadband and narrowband scenarios) trans-surfaces have been designed and simulated, providing good results for normal incidence.
A novel topology and a systematic procedure for the design of wideband linear-to-circular polarization converters are presented. The proposed configuration consists of three anisotropic inductive sheets, separated by two dielectric spacers. The dispersion curves for the two polarizations are engineered to achieve a broadband, linear phase response. The design procedure maximizes the differential phase...
This paper presents an all-metal parallel plate waveguide (PPW) Luneburg lens designed using an array of subwavelength Fakir bed of nails unit-cells. Variation of the metal post height and PPW-spacing modulates the effective refractive index. The lens operates in the Ku-band of frequencies, with more than 40% bandwidth, in a quasi-TEM mode. Broadband and low loss, with high directivity and wide field-of-view,...
The design of a small printed-log-periodic antenna, loaded with an active matching network, for multiband applications is presented. A well-known, low-cost and low-profile antenna is re-engineered for including an additional impedance bandwidth in the lower UHF-band. The design method includes the use of the recently introduced sensitivity parameter Sens in order to find a suitable location for a...
This paper extends the study of a previously proposed wideband implantable antenna designed to operate at superficial level in the muscle, as part of a passive medical sensor. The antenna covers the frequency band between 1.4 GHz and 4.2 GHz and is compatible with the integration of an energy scavenging circuit. In the present paper we assess experimentally the antenna time-domain performance and...
This paper presents a high-gain 6–40 GHz circularly polarized antenna system designed for a 6U CubeSAT mission for monitoring RF emission from earth. The antenna system consists of three quasi-tapered helical antenna elements, operating at 6–11 GHz, 11–22 GHz and 21–40 GHz, respectively. Each antenna element is designed to produce an end-fire beam with its helical diameter varying along its axis to...
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