This article applies an in-house generalized ray-tracing (RT) model to efficiently compute both the radiation pattern and the efficiency of geodesic lenses with nonrotationally symmetric shapes. Losses due to ohmic effects and surface roughness are included in the model. These losses are very relevant for monolithic geodesic lens antennas as postprocessing techniques cannot be applied to reduce the surface roughness of internal part of the metallic plates. The model is validated by comparison with full-wave simulations for three different lenses: a circular flat parallel-plate waveguide (PPW), an elliptically compressed geodesic lens, and a water-drop lens. These results show a reduction in computational time by a factor of 600 using the RT model. A non-rotationally symmetric water drop lens has been manufactured in a monolithic piece using the laser powder-bed fusion (LPBF) technique with successful experimental results.

The Physical Optics (PO) method is used to derive simplified expressions to compute the radiation electric fields of planar graded-index and geodesic lenses based on a parallel-plate waveguide (PPW) implementation. If the PO method is combined with ray-tracing (RT) techniques, the resulting RT-PO procedure is capable of computing radiation patterns and gain of the PPW-based lens antennas when their apertures have a general shape and the electric field is vertically polarized. The RT-PO method is validated by comparing it with the full-wave simulation results of the commercial software ANSYS HFSS for three application cases. The results show that the RT-PO approach is not only very efficient from a computational point of view but also accurate, thus being a very convenient analysis/design tool for this kind of antenna.

Antennas for future communication systems are required to be highly directive and steerable to compensate for the high path loss in the millimeter-wave band. In this work, we propose a linear array of modulated geodesic Luneburg lens (the so-called water drop lens) antennas operating at 56-62 GHz. The lens array antenna features 2-D beam scanning with low structural complexity. The lenses are fully metallic and implemented in parallel plate waveguides (PPWs), meaning that they are highly efficient. Each lens is fed with 13 rectangular waveguides surrounded by glide-symmetric holes to suppress leakage. The lenses provide 110? beam coverage in the H-plane with scan losses below 1 dB. In order to scan in the E-plane, we use a feeding network based on a 1:4 power divider and three phase shifters. In this configuration, the array can scan 60? in the E-plane, albeit with higher scanning losses than in the H-plane. The lens array is manufactured and a good agreement between simulated and experimental results is obtained.

Fully metallic geodesic lens antennas are popular for millimeter-wave band applications due to their simplicity, robustness, and low loss. Here, we report the experimental results of a geodesic lens array antenna, which was specifically designed to be additive-manufactured in one single piece using laser powder-bed fusion (LPBF). LPBF in aluminum alloy AlSi10Mg is able to produce high conductivity and relatively low surface roughness, so the antenna is highly directive and efficient. In addition, LPBF increases the robustness of the design since the lens array is monolithic, i.e., the risks associated with the assembly, including misalignments and undesired air gaps between pieces, are totally eliminated.

The geodesic Luneburg lens has been revisited as a suitable solution for applications requiring directive beams in the millimeter waveband. Among its advantages, its rotational symmetry and high efficiency stand out. However, one of its drawbacks is the need for a certain height to produce the desired focusing properties of the lens. Here, we propose a low-profile solution based on rotationally symmetric ridges that mimic, similar to geodesic lenses, the effective refractive index of a Luneburg lens. Moreover, we show that both rectangular and trapezoidal ridges perform similarly, opening the possibility for other manufacturing techniques. We demonstrate this concept with a prototype that is fully metallic and provides a scanning range of +/- 62 degrees over a broadband of operation, from 24 to 34 GHz. In this prototype, the height of the lens is 18 times more compact than the original Rinehart-Luneburg lens, allowing the lens to be vertically stacked, which is beneficial, for example, for producing linear arrays. This technique could be used to produce other type of lenses.

The current worldwide energy and economical crisis has triggered the need for more sustainable technological solutions to implement energy-efficient next generation communication systems, which should also be commercially viable and cost-effective. Moreover, future terrestrial and satellite communications will bring a wide range of use cases, services, and environments with very different requirements and specifications to ful-fill in order to generate a smart digital, fully connected society. Designing new antennas for each single application is not feasible since it is very complex to meet the customer's demand in the short run, and antenna system solutions that are easily re-configurable to be re-used in diverse scenarios are needed. The combination of lenses with traditional phased array antennas (also known as dome antennas) is a promising way of mixing the advantages of both antenna technologies and optimizing the performance of our systems depending on the use case scenario. This article discusses the industrial and technical potential of using dome antennas implemented in different technologies for expected use cases and applications of future terrestrial and satellite communication systems.

Integrating dielectric lenses with phased array antennas can be beneficial in numerous applications, yet the design procedure typically requires significant computational effort. In this work, we employ a streamlined in-house two-dimensional ray-tracing model to design dielectric lenses, with the goal of enhancing the gain of an array antenna at large scanning angles. The ray-tracing model also accounts for losses from material absorption and reflections. The interfaces between the dielectric layers of these lenses devised in this study are defined using splines to allow a large flexibility of their shape. First, dielectric lenses consisting of a core layer supplemented by two matching layers are investigated. The results show better performance compared to the lens constructed using the conic equation. In addition, multilayer dielectric lenses also provide more flexibility, as proved by the proposed configuration with five layers which also minimizes reflections in the optimized direction. Finally, a nonuniform multilayer lens, featuring two layers on the sides and a single layer near to broadside can improve gain at 60∘ while maintaining efficiency at smaller angles.