A monopulse horn feed with a triple radiation pattern (sum, elevation difference and azimuthal difference) operating at 35 is presented. The device consists of three main parts: a spline profiled horn, a mode converter that generates the modal field combinations that produce each radiation pattern, and a very compact single-layer monopulse comparator network. Unlike other state-of-the-art designs, the novel feed is based on a triple radiation pattern horn with a mode converter excited by a comparator network implemented in a single level for improving the compactness and easing a quasi 2D manufacturing. The kernel of this network is a novel 180∘ H-plane waveguide coupler with in-line ports, which avoids any additional phase compensation in the routing waveguide sections used in other works. The design process of the Ka-band antenna feed is described, and simulated results for the three radiation patterns and their associated reflection coefficients are presented. The prototyping process is outlined and the obtained experimental results are compared with the simulated ones showing very good agreement and validating the design process.

This article proposes an original structure of evanescent quadridge antenna (EQA) to conceive dual-polarized full-metal front-ends that can be used in active antennas (AAs) with wide field-of-view (FoV). An original design methodology is here proposed that allows to induce radiation from subwavelength squared apertures based on the use of evanescent and quadridge waveguides. The proposal is illustrated by means of a design with 4.5% bandwidth providing dual-circular polarization (CP) with good performance up to 50°-scanning even in the diagonal plane. For comparison purposes, a metallic benchmark is also proposed, which is based on the use of classical quadridge horns. Such comparative analysis allows to understand the superior performance of the proposed concept and its main advantage: it allows to avoid the excitation of the first high order mode in the squared quadridge aperture. The excitation of such spurious mode in the antenna is explained in terms of simple equivalent circuit models characterizing the aperture periodic discontinuity.

In this work a heuristic optimization algorithm known as the Fruit fly Optimization Algorithm is applied to antenna design problems. The original formulation of the algorithm is presented and it is adapted to array factor and horn antenna optimization problems. Specifically, it is applied to the array factor synthesis of uniformly-fed, non-equispaced arrays and to the profile optimization of multimode horn antennas. Several numerical examples are presented and the obtained results are compared with those provided by a deterministic optimization based on a simplex method and another well-known heuristic approach, the Genetic Algorithm.

This work presents the design and prototyping of a reconfigurable phased array in Ku band (16 to 18 GHz) implemented in waveguide technology. The design is based on the use of a novel seamless waveguide module integrating four reconfigurable phase shifters to adjust the relative phase shift between the unitary elements of a linear array, which are illuminated uniformly by a corporate waveguide feeding network. The phase shifters are implemented by a 90° hybrid coupler in waveguide technology where two of its ports are loaded with a tunable reactive load, implemented in this proof of concept with a tuning screw. The four phase shifters have been manufactured in a single part using direct metal laser sintering, avoiding the losses related to bad electric contacts and misalignments associated to multipart devices. This also simplifies the assembly of the full phased array, leading to a modular approach with three parts whose design can be addressed separately. The experimental results for the complete array antenna show great performance and demonstrate that the main-lobe of the radiation pattern can be effectively scanned continuously between the angles −25° and 25°, with a high efficiency in the whole design band thanks to the proposed waveguide implementation.

This work presents a new topology of evanescent mode filter (EMF) that allows for its efficient additive manufacturing (AM). Chamfered ridges which avoid the appearance of undesired supports when printed vertically (i.e., along the propagation axis of the filter) are considered. This strategy ensures accurate tolerances, reduced cost and it also enables monolithic manufacturing of the EMF as part of a feed chain. A circuit model is developed to explain the behavior of the new ridges as well as to speed up the overall filter design. The proposed concept and methodology are validated experimentally through the manufacturing and measurement of a prototype.