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A multibeam antenna system fed by a compact Rotman lens is presented in multilayer substrate integrated waveguide (SIW) technology. The lens is implemented in two layers using a new transition based on several star-shaped coupling slots and an SIW integrated reflector. Compared to standard rectangular coupling slots, this transition is broadband and maximizes power transfer between the two layers of the lens regardless the position of the beam port along the focal arc of the Rotman lens. The radiating part is an array of 15 slotted waveguides. These waveguides are centrally fed to enhance their bandwidth and reduce the “long line effect.” To validate the proposed concepts, an antenna system has been prototyped at 24.15 GHz. The designed transition leads to a physical size reduction of about 50% for the Rotman lens, and more than 33% for the antenna footprint compared to standard single-layer implementations. The experimental results demonstrate a scanning range of \pm 33^\circ and a 4% bandwidth for \textVSWR < 2; the isolation between input ports is better than - 10\;\textdB. [ABSTRACT FROM PUBLISHER]

We describe here an optimization procedure to shape the radiation pattern of planar two-dimensional (2-D) leaky-wave antennas. The structures under investigation are superstrate configurations made by partially reflecting screens (impedances sheets) over a ground plane and excited by open-ended waveguides. The antenna configuration providing the required radiation pattern is obtained by resorting to an ad hoc optimization procedure that minimizes the mean squared error between the target pattern and the actual radiated far field. The radiated field is analytically evaluated using a Green’s function spectral approach to speed up the optimization process. Several kinds of radiation patterns can be obtained using the proposed algorithm. In this work, we focus our attention on flat-topped radiation patterns, suitable as element pattern for phased array antennas covering a limited angular field of view such as those considered for space applications. The proposed procedure is validated by full-wave results and measurements. [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 novel multibeam antenna based on a \mathbf4 \times \mathbf4 Butler matrix with sidelobe level (SLL) control is proposed in the 60-GHz band. The SLL is controlled using a dedicated circuit composed by four 90-degree couplers with different coupling factors and several cross couplers. This dual-layer antenna is made by hollow waveguides and is assembled using diffusion bonding technique. The radiating part is a compact array of ridged waveguides designed to avoid appearance of grating lobes in the visible range for large scanning angles. The antenna field of view is \pm \mathbf43^\circ with sidelobes lower than - \mathbf17.5\;\mathbfdB over the entire scanning range. The isolation between the input ports of the Butler matrix is better than 25 dB at the design frequency of 61.5 GHz. The reflection bandwidth for VSWR < \mathbf2 is larger than 6.5%. At the design frequency, the measured conductor losses of the antenna are estimated lower than 0.64 dB for all ports. [ABSTRACT FROM PUBLISHER]

The use of dielectric super-layers for shaping the radiation pattern of focal plane feeds of a multibeam reflector system is discussed. Using the super-layers, it is possible to reduce the spillover from the reflectors without increasing the dimension of each aperture. The effect has been demonstrated using a realistic array configuration. The experimental demonstration is obtained with configurations which are typical for satellite based multi beam telecommunication links. Thanks to the adoption of a \times \,4 reuse scheme, based on frequency and polarization orthogonal channels, the measured edge of coverage directivity has improved, with respect to a standard technology case, by 2 dB over an operational bandwidth of about 2%. [ABSTRACT FROM PUBLISHER]

This work proposes a novel multi-beam leaky-wave pillbox antenna. The antenna system is based on three main parts: feeding part (integrated horns), quasi-optical system and radiating part. The radiating and input parts are placed in two different stacked substrates connected by an optimized quasi-optical system. In contrast to conventional pillbox antennas, the quasi-optical system is made by a pin-made integrated parabola and several coupling slots whose sizes and positions are used to efficiently transfer the energy coming from the input part to the radiating part. The latter consists of a printed leaky-wave antenna, namely an array of slots etched on the uppermost metal layer. Seven pin-made integrated horns are placed in the focal plane of the integrated parabola to radiate seven beams in the far field. Each part of the antenna structure can be optimized independently, thus facilitating and speeding up the complete antenna design. The antenna concept has been validated by measurements (around 24 GHz) showing a scanning capability over \pm 30^\circ in azimuth and more than 20^\circ in elevation thanks to the frequency scanning behavior of the leaky-wave radiating part. The proposed antenna is well suited to low-cost printed circuit board fabrication process, and its low profile and compactness make it a very promising solution for applications in the millimeter-wave range. [ABSTRACT FROM AUTHOR]