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In this paper, a novel compact microstrip patch antenna with a boresight filtering gain response is proposed. The proposed antenna consists of a radiating patch, a ground plane, two pairs of slots respectively etched on the radiating patch and the ground plane, two shorted vias connecting the radiating patch and the ground plane. The slots on the ground plane not only provide a gain null in the lower transition band, but also introduce a new low‐resistance resonance which is beneficial to widen the impedance bandwidth. The slots on the radiating patch provide another gain null in the upper transition band. The two shorted vias are used to further adjust the reflection coefficient and the gain performance of the antenna. Since no extra circuits are introduced, the proposed antenna is compact. A prototype operating at 3.0 GHz was fabricated and measured. It demonstrates that the proposed antenna has a bandwidth of 3.5% and a gain of 6.0 dBi in a profile of 0.015 λ0. At the same time, a good filtering gain response is realized. [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]

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]

A measurement method of an active element antenna pattern in a hybrid antenna array with heterodyne architecture under a real environment is proposed and applied to the design of an ultralow sidelobe level scanning array. To avoid the phase uncertainty caused by the local oscillator signal in the heterodyne architecture, a phase‐normalized active element pattern (PNAEP) is used to characterize the element antenna patterns of both amplitude and phase. The PNAEP has almost taken account of all the practical factors of an array, such as mutual couplings, various types of element antennas, unequal spacing, or diverse environmental effects. The PNAEP is measured with a 16‐element scanning receiving array with a heterodyne architecture to validate the feasibility of the PNAEP. Based on the PNAEP, the scanning array achieve an ultralow sidelobe level of −33 dB. Applying to various receiving array architectures the PNAEP method is a feasible and universal tool for array synthesis and optimization under real environments. [ABSTRACT FROM AUTHOR]

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]

An exponential tapered post‐wall slotline antenna loaded with dielectric lens is proposed and demonstrated. The theoretical profile of the loaded dielectric lens is derived, and its physical explanation is presented. Besides, the proposed post‐wall structure in the antenna ensures low available characteristic impedance as well as low cross‐polarization levels of the antenna. The proposed antenna exhibits an 18.12 GHz impedance bandwidth between 1.88 and 20 GHz and a peak gain of 10.9 dBi. The measured E‐plane and H‐plane cross‐polarization level is −37.0 and − 26.0 dB in boresight direction, respectively. Compared to the antenna without dielectric lens, the average gain of the proposed antenna increases by 3 dB from 14 to 20 GHz, and the pulse peak‐peak gain increases by 1.59 dB, and the tailing signal levels is about 0.35 dB lower. [ABSTRACT FROM AUTHOR]

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]