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We present the experimental validation of the dual-mode, polarization-agile parallel-fed continuous transverse stub (CTS) antenna architecture introduced in Part I of this two-part paper. The Ka-band dual-mode CTS array described in Part I is characterized when it radiates in horizontal and vertical polarization. To this end, it is combined with two different quasi-optical beamformers operating in a quasi-transverse electromagnetic (quasi-TEM) and in a quasi-transverse electric (quasi-TE1) mode, respectively. The scanning capabilities of both multibeam antenna systems are demonstrated. The CTS array and its feed network comprising corrugated parallel-plate waveguides (CPPWs) are fabricated by additive manufacturing. Measurements show that the dual-polarized CTS antenna works between 29 and 32 GHz in a field of view of about 45°, achieving a peak gain of 31.3 dBi and very low cross polarization. These promising results pave the way for the realization of dual-circularly polarized beam-scanning antennas with application to broadband and compact Ka-band ground terminals. [ABSTRACT FROM AUTHOR]

An amplitude-comparison monopulse slotted waveguide antenna array with a pillbox parabolic quasi-optical beamforming network is proposed in substrate integrated waveguide (SIW) technology in the 24 GHz band. The beamformer is illuminated by a cluster of horn pairs located in the focal plane of the pillbox reflector. Each horn pair is composed of two H-plane sectorial horns connected to a coupler. In-phase and out-of-phase operations of each horn pair allow radiation of the $\Sigma $ and $\Delta $ beams along the antenna scanning plane (E-plane). At the design frequency of 24.15 GHz, the experimental results demonstrate an antenna field of view of ± 26°, with null depth better than −20 dB for all the measured $\Delta $ beams. The antenna gain varies between 21.6 and 20.5 dBi for the $\Sigma $ beams and the measured input reflection bandwidth is about 2.4% for VSWR < 2. [ABSTRACT FROM PUBLISHER]

This paper presents a flat, high gain, wide scanning, broadband continuous transverse stub (CTS) array. The design procedure, the fabrication, and an exhaustive antenna characterization are described in details. The array comprises 16 radiating slots and is fed by a corporate-feed network in hollow parallel plate waveguide (PPW) technology. A pillbox-based linear source illuminates the corporate network and allows for beam steering. The antenna is designed by using an ad hoc mode matching code recently developed for CTS arrays, providing design guidelines. The assembly technique ensures the electrical contact among the various stages of the network without using any electromagnetic choke and any bonding process. The main beam of the antenna is mechanically steered over $\pm 40^\circ$ in elevation, by moving a compact horn within the focal plane of the pillbox feeding system. Excellent performances are achieved. The features of the beam are stable within the design 27.5–31 GHz band and beyond, in the entire Ka-band (26.5–40 GHz). An antenna gain of about 29 dBi is measured at broadside at 29.25 GHz and scan losses lower than 2 dB are reported at $\pm 40^\circ$. The antenna efficiency exceeds 80% in the whole scan range. The very good agreement between measurements and simulations validates the design procedure. The proposed design is suitable for Satcom Ka-band terminals in moving platforms, e.g., trains and planes, and also for mobile ground stations, as a multibeam sectorial antenna. [ABSTRACT FROM PUBLISHER]

A multibeam pillbox antenna system incorporating monopulse phase comparison technique is proposed in the 24-GHz band. This low-profile antenna architecture combines the scanning capabilities of pillbox configurations and enhanced resolution of two-quadrant monopulse technique; this approach avoids mechanical orientation of the antenna system for tracking applications. The radiating panel consists of two subarrays of 23 slotted waveguides, with 8 slots per waveguide. The beam is scanned in E-plane over a field of view of \pm \bf 40^\circ , and sum/difference patterns are generated in H-plane. Around the design frequency, \bf f = \bf 24.\bf 15\,\bf GHz, the antenna gain varies between 25 and 21.5 dBi for the central and extreme beams, respectively. The measured null depth is better than - \bf 16\;\textdB for all difference beam patterns. The antenna bandwidth for \bf VSWR < \bf 2 (\textbfS\textbf{ii} < - {\bf 10}\;\textbf{dB}) and isolation better than \bf 10\;\bf dB (\textbfS\textbf{ij} < - {\bf 10}\,\textbf{dB}) is equal to 4.5%. [ABSTRACT FROM PUBLISHER]