Search

A spoof surface plasmon polariton (SSPP) antenna with dual-band endfire gain and small frequency ratio (FR) is presented. It uses an asymmetric structure to support two independent surface waves with different nonlinear phase constants. Due to the different phases of the superposed $E$ -field at the terminal of the proposed structure, dual-band endfire gains and endfire radiation null are achieved. The odd- and even-mode feedings, providing additional phase differences, are also investigated. Three prototypes, with FRs of 1.06, 1.11, and 1.5, are designed, simulated, and measured, respectively. All results validate the mechanism and demonstrate that the FR of the proposed antenna can be achieved easily in the range of 1.06–1.5 by choosing different unit cells and feeding modes. Moreover, the measured endfire out-of-band gain suppression, over 17 dB, presents a good directional interference inhibition. This small-FR endfire antenna shows a broad prospect for band coverage and directional noise inhibition with very close operating frequencies. [ABSTRACT FROM AUTHOR]

A high-fidelity short-pulse monopulse antenna based on an extended Goubau line (EGL) is proposed, along with a novel time-domain analyzing and designing method. The monopulse antenna contains a simple feeding network and an EGL radiating structure, where the width of the single conductor is enlarged and a metal wall is constructed along the central line of the conductor. The antenna is actually a two-element array to form sum and difference patterns. Performances of the feeding structure and the EGL are almost independent of operating frequency, ensuring the antenna to transmit and receive short-pulse signals with high waveform fidelity. Angular information is obtained by analyzing the received pulses with the normalized Euclid distance (NED). The NED patterns are plotted to illustrate the angular information provided by the short-pulse monopulse operation. A null depth of 30 dB is obtained by the difference NED pattern for the short pulses with a spectrum from 4.2 to 11.8 GHz. The measured performance shows that the proposed short-pulse monopulse antenna has a promising prospect in directional detecting and tracking applications. [ABSTRACT FROM AUTHOR]

A metasurface lens antenna fed by a planar $8\times8$ dual polarized antenna array is proposed and characterized for full-dimensional massive multiple-input multiple-output (MIMO) and multibeam systems at sub-6 GHz bands. The lightweight multilayer metasurface structure consisting of Jerusalem cross elements is used for a planar lens design. The lens antenna with the size of $10\lambda _{0} \times 10\lambda _{0} \times 5\lambda _{0}$ is fed by an $8\times8$ dual-polarized stacked patch array to operate over the range from 5.17 to 6.10 GHz, where $\lambda _{0}$ is the free-space operating wavelength at the center frequency of 5.6 GHz. This article shows the scanning range of ±25° with a maximum gain of 22.4 dBi and the gain variation of 3.3 dB at 5.6 GHz. Beam coverage performance, pattern envelope correlation coefficient, and port isolation properties demonstrate its full-dimension access capability of the antenna. Besides, the multibeam antenna system with high-gain coverage is achieved by beams operating at the same frequencies, while the frequency division multiplexing can be realized for the isolated beams. The proposed metasurface lens antenna, featuring lightweight, compactness, and low cost compared to a 3-D dielectric lens and low-complexity compared to the array scenarios, can be an alternative for fifth-generation (5G) sub-6 GHz frequency bands. [ABSTRACT FROM AUTHOR]

A postwall slotline (PWS), composed of a bilateral slotline and two metalized via arrays aligned at the slot edges, is proposed and its application in the design of short-pulse tapered slot antennas (TSAs) is investigated. The characteristic impedance of the PWS is derived by a partly analytical and partly empirical method. Compared with the conventional slotline, the PWS has lower available characteristic impedance and larger variation range, which is favorable for meeting diverse design specifications. The PWS is employed in the design of two TSAs with exponential profile and Gaussian profile, respectively. The two tapered PWS antennas are fabricated and their performance in both frequency domain and time domain is investigated. The results show that the TSA based on the PWS is featured by broad bandwidth, low cross-polarization, and good suitability for short-pulse applications. [ABSTRACT FROM PUBLISHER]

This study presents a hybrid receiving array architecture that combines analog and digital beamforming to offer a solution for the phased-array feed and other multifunction receive-only applications. This architecture is capable of handling multiple beams forming simultaneous and precision beam steering. To further reduce the hardware counts of the online performance monitoring, a calibration method is proposed in which none of the transmitters or the dedicated distribution network are used. The hybrid architecture concept and built-in calibration are validated experimentally via a prototype. The system performance, including the statistical results of the baseband measurement, phase error, and radiation patterns under various array configurations, are illustrated. An effective phase tuning step of 0.1^\circ, as well as a steering resolution at the subdegree level, is achieved, and the measured aperture distribution is in good agreement with that derived from the proposed online calibration. [ABSTRACT FROM PUBLISHER]

Signal space method for time-domain characterization of short-pulse networks and antennas is presented and described. The short-duration pulses, which are usually recognized as energy signals, belong to the signal space L^2 (\Re) . By means of the signal space analysis, the Euclid distance on L^2 (\Re) is related to fidelity and amplitude ratio, and thus can be used for comprehensively characterizing short-duration pulse waveform distortion and amplitude variation, resulting in an overall description of networks and antennas. Three numerical examples, microstrip transmission line, microstrip pulse power divider, and antipodal Vivaldi antenna, are given to demonstrate the usage and significance of this method for characterization of networks and antennas. [ABSTRACT FROM PUBLISHER]