This article presents the design of a dual-lens beamformer in multilayer printed circuit board (PCB) technology. The proposed lens is implemented in a dielectric parallel-plate waveguide (PPW), offering enhanced scanning performances along with a compact design. A combination of ray-tracing and conjugate field matching is used to design the lens and feed configuration. The concept is validated by a prototype operating in the downlink K-band allocated to satellite communications (17.3-20.2GHz). The shaped lens is machined from a stack of substrate layers, while the integrated feed system is realized using standard PCB techniques. The final structure produces nine stable beams over an angular sector of +/- 60 degrees (+/- 10 beamwidths) from a flared linear aperture of about 14 lambda . Good agreement between the simulated and experimental results is obtained. The measured return loss is better than 10dB, and port-to-port isolation is greater than 17dB over the entire frequency band. The estimated radiation efficiency of the antenna is about 75%, and maximum scan losses are in the order of 2dB.

In this paper, the design of a continuous parallel-plate lens in multilayer PCB technology is presented. The beamformer consists of a continuously shaped lens doublet made from a stack of substrate layers and an integrated SIW feed system. Asymptotic techniques are used to optimize the lens and feed geometries. The proposed concept is validated by full-wave simulations of a lens design operating in the K-band (17.3-20.2 GHz). The final structure is matched to free-space using a linear flare and provides a total of nine beams over a $\pm 60^{\circ}$ sector with low scan losses in the order of 2 dB.

Automotive radars are designed to enhance road user safety and reduce the number of accidents on public roads and there is a constant demand to improve the performance for these radars. In this paper, a novel proof-of-concept multiple-input multiple-output (MIMO) radar architecture is presented by frequency modulated continuous waveform (FMCW) transmission. For enhanced angular resolution, the radar uses a two-tier antenna setup leading to a sparse array arrangement, mainly in an effort to mitigate grating lobes and to offer different illuminations of the same scenario. Also, the experimentally verified sparse radar antenna designed for target detection at the receiver, achieves modest sidelobe levels and grating lobes well below 12 dB from the main beam maximum, whilst still maintaining competitive half-power beamwidths when compared to more conventionally spaced arrays. Moreover, the high impedance bandwidth of this receiver array and the supporting radar electronics (more than 6%) allows for the detection of targets at only a 10 cm spatial separation. The complete system is also capable of seeing a wide field-of-view (FOV) since it utilizes a network of radar modules to cover the forward −90$^\circ$ to +90$^\circ$ angular range by sectorization. In the best case, the measured radar system can resolve targets that are a distance of just $\pm 2^\circ$ apart in angular separation.

This article presents a parallel-plate lens beamformer for continuous wide-angle scanning. The design is based on a compact dual-lens system with extended scanning range and is optimized using a previously developed geometrical optics technique. Beam steering is accomplished with a mechanical feed system based on the noncontact characteristic of groove gap waveguides, offering large bandwidth, low profile, and mechanical ruggedness. The proposed concept is validated by an all-metal prototype of a $20.5\lambda $ lens operating in the uplink Ka-band allocated to satellite communications (27.5–31 GHz). Good agreement is obtained between the simulated and measured performances. The measured return loss is greater than 12 dB over the entire frequency band and beyond. High scanning performances are achieved over an angular range of ±50° (±14 beamwidths), with maximum scan losses in the order of 3 dB and good pattern stability over the entire band. The proposed solution is particularly suited for next-generation satellite terminals requiring compact broadband antennas with continuous beam-steering capability over a large angular range.

This paper presents a parallel-plate waveguide lens for wide-angle mechanical beam steering. A previously developed ray-tracing procedure is used for designing the quasi-optical system. The feed system is based on gap waveguide technology enabling a simple and rapid mechanical actuation. Validation of the proposed concept is given by numerical results for a Ka-band lens design. A high scanning performance over an angular range of ± 50° with a worst-case scan loss of about 3 dB is achieved. The simulated return loss is greater than 15dB in the 27.5-31 GHz band. The proposed lens beamformer is an attractive ground-segment solution for future Satcom applications.

In the context of a competitive 5G environment, satellite systems must be able to provide cost-effective solutions to complement terrestrial networks. In a preliminary paper, the achievable capacities of diverse LEO satellite payloads were computed as a function of a parameter characterising the non-uniformity of the users distribution in the satellite field of view. As the non-uniformity parameter increases, the capacities of the various payloads benchmarked decrease because of inter-beam interference and shortage of frequency resource. A way to mitigate this capacity loss is to use flexible payloads with adaptive capabilities such as beam steering or flexible resource allocation. This paper proposes to extend the study to MEO payload and antenna architectures and benchmark them with respect to the capacity they can achieve and the power they require. A Circular Direct Radiating Array with Digital Beam Forming, a Sparse Direct Radiating Array with Digital Beam Forming as well as an architecture implementing Hybrid Beam Forming are analysed in terms of effective capacity achieved on different scenarios of users distributions with varying non-uniformities. The application of these results on a realistic scenario of user distribution concludes on the most promising payload architecture.

A parallel-plate waveguide lens with mechanically reconfigurable feed network for continuous beam scanning is presented. The quasi-optical system is designed using an optimization process based on previously developed ray-optical methods. The feed network relies on the non-contacting properties of groove gap waveguides which allows for a fixed input port and simple mechanical actuation. Numerical results are presented for a Ka band lens design, demonstrating a high scanning performance over an angular range of +/- 35 degrees with scan losses lower than 2 dB; the simulated mismatch loss is lower than -15 dB between 27 and 31 GHz. The proposed all-metal beamformer is therefore a promising solution for next-generation Satcom applications.

A physical optics (PO) method for computing the focal-region fields of a parallel-plate waveguide (PPW) lens is presented. A simplified delay line model is used to represent the delay section between inner and outer lens profile. The lens is analyzed by assuming a plane wave incident on the outer contour. For a given lens geometry, the resulting maximum field loci at different angles of incidence are reported. The close agreement with full-wave results by a commercial simulator validates the applicability of the underlying two-dimensional (2D) lens model. The developed tool is several orders of magnitude faster than the general purpose full-wave simulation and therefore presents an efficient auxiliary tool for the design of lens feed networks.

In this paper, a novel millimetre-wave radar for collision avoidance and automotive applications is presented. The system uses frequency modulated continuous-wave (FMCW) transmission based on multiple input multiple output (MIMO) substrate-integrate waveguide (SIW) antennas operating in the K-band regime. The continuous sawtooth time-domain wave transmitted from two SIW antennas, by time-domain multiple access (TDMA), is detected with a half-lambda spaced four-element SIW receiver array at a distance of 4 meters in a calibrated anechoic chamber and verified with simulations. The high bandwidth and omnidirectionality of the SIW antennas in the horizontal plane, together with digital-beamforming for the achieved MIMO virtual array, offers an overall field-of-view of 130 degrees for the radar system. Also, the MIMO radar achieves an angular resolution of 14 degrees and offers a range resolution of 10 cm at a cost of only 6 transmitter and receiver elements in total.