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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]

An endfire frequency scanning tapered slot antenna (FSTSA) is proposed and investigated. The proposed FSTSA is a two-conductor structure with a gradient slots array etched only on one of two inner edges in the FSTAS. The asymmetrical inner edges enable the antenna to excite two modes with different phase constants simultaneously along the two inner edges. Due to dispersion characteristics of spoof surface plasmon polaritons (SSPPs), the phase difference between the EM waves along the two conductors changes versus frequencies, which enables the main lobe of the FSTSA to scan through the endfire direction. An analysis model is conceived to provide insights into the design, which accurately predicts main lobe directions and initial values of the proposed antenna. The proposed antenna is fabricated, and the measured results show that the main lobe of the antenna scans from −15° to 14° (endfire direction at 0°) from 6.60 to 7.70 GHz, with the scanning rate of 26.4°/GHz. This antenna could be suitable for radar, plane integrated communication system, and certain other beam-scanning applications. [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 novel phase corrected substrate integrated waveguide (SIW) H-plane horn antenna with embedded metal-via arrays is presented. The SIW horn is divided into four subhorns by three metal-via arrays inside the horn. A uniform phase distribution of EM field across the horn aperture is achieved by adjusting the lengths and positions of the metal-via arrays. The proposed horn antenna has a compact profile, and its simulated gain is 7.50 dBi at 35.5 GHz, whereas the simulated gain of a traditional horn antenna without the metal-via arrays is 6.38 dBi. When measured, the gain of the proposed horn antenna is 7.87 dBi at 35.5 GHz, whereas the gain of the traditional horn antenna is 5.58 dBi. Good agreement between the simulated and the measured results is obtained. [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]