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An active transmitarray antenna is presented for Ka-band monopulse tracking radar in the 34-36-GHz range. A novel contribution is the application of commercial SiGe-based 5G beamforming chips in a large-scale naval radar array, demonstrating how developments in Ka-band communications can benefit radar technology. Three arrays of 0.77 m diameter each with 24368, 19424, and 7824 radiating elements are presented to compare amplitude-tapered, space-tapered, and hybrid-tapered designs. All designs achieve a sub-1° half-power beamwidth (HPBW), peak sidelobe levels (SLL) below -26 dB, and effective isotropic radiated power (EIRP) of 100 dBm at broadside with a ±60° grating-lobe-free scan range. Furthermore, a small-scale demonstrator is realized and presented that consists of an eight-layer printed circuit board (PCB) with 8× 8 patch antennas on one side and a 4× 4 open-ended waveguide (OEWG) feed-array with beamforming chips and integrated liquid cooling channels on the other side. After over-the-air calibration, the realized array achieves a peak EIRP of 56 dBm, a 12° HPBW, and the ability to scan to ±60° in the H-plane with cos θ scan loss and no grating lobes. E-plane scanning is achieved up to ±45° with θ 1.1 scan loss.

This paper presents the design of a Ka-band active transmitarray consisting of radiating waveguide elements, a transition from waveguide to PCB, and commercial phase shifters and high-power amplifiers. A unit cell design is presented, which at a size of (0.7λ)2 allows for beamsteering without grating lobes up to around ±20° from broadside. The modeled performance of a 68-element array is presented, demonstrating the feasibility of a 81.6 dBm EIRP at 35 GHz from a 7 cm wide aperture.

Fixed-beam, high-gain antenna systems can be used for a finer partitioning of the currently used cell-sectoring. This partitioning has the benefit of reducing the number of users seen per antenna beam, which reduces interference. Furthermore, the high antenna gain allows for a high effective isotropic radiated power while keeping the transmit power low. In this paper, we study the performance of such a fixed-beam, high gain antenna system design for millimeter-wave mobile communications. The antenna system is designed to keep the inter-sector interference in a multi-site scenario low. The performance is analyzed for single- and multi-user environments. In single-input single-output mode, the 50th percentile of the signal-to-interference-plus-noise ratio lies between 12.5 dB to 39.7 dB if 3 to 0 interferers are present, respectively. For multiple-input multiple-output transmission using zero-forcing, the signal-to-interference-plus-noise ratio increases and the 50th percentile ranges from 36.1 dB to 43.3 dB if 3 to 0 interferes are present, respectively. By using maximum ratio transmission, the best performance is achieved with no interferers present, while a plunge in performance is observed with interferers. Furthermore, the study revealed that the narrow beam antenna system can also provide a clear signal separation for small spatial separations. In the given example, the signal-to-interference-plus-noise ratio is larger than 32.1 dB with 11 active antenna elements, where 2.8 meters separate the users. Hence, the paper shows that the cell-partitioning antenna systems provide coverage in the desired area while keeping the inter-sector interference low, and the considered transmission techniques can be used for situation optimized mobile communication links.

Antenna and low-noise amplifier (LNA) co-design is a promising method for increasing the sensitivity of millimeter-wave (mmWave) receiver systems. Co-design involves several individual steps which usually do not intersect with each other in one design flow, but this method combines all of them together and allows to obtain mutual benefits for all components. This paper gives an overview of several different mmWave engineering tasks like antennas and monolithic microwave integrated circuit (MMIC) design together with RF interconnection solutions like wirebonding, flip-chip and packaging technology. The suggestion of the mmWave receiver co-design for achieving minimum noise figure at low costs is also provided.

A V-band Vivaldi antenna design for beyond-5G base station applications operating within V-band is demonstrated. The device can be used for interfacing with radio-over-fibre links and optoelectronic components through a coplanar waveguide to slotline transition. Simulations show an end-fire radiation with a 3 dB gain bandwidth ranging between 46.9-77.4 GHz combined with the reflection coefficients remaining below-10dB for the same frequency range. A comb structure inspired by optical grating couplers is added providing an increased maximum gain of 12.6 dBi at 68.5 GHz. Measurement results validate the promising characteristics of the planar antenna.

This paper presents a review of various outphasing methods. Key performance indicators are formulated focusing on reliability, energy consumption and bandwidth and are used to compare state-of-the-art outphasing methods. Outphasing methods which show potential for beyond-5G base station applications are described and relevant advantages, disadvantages and literature gaps are pointed out. Specifically, the recent developments on using antenna elements to be co-designed with an outphasing system will be considered as a promising efficient solution. Findings in this paper show that a co-designed amplifier-antenna outphasing system achieves one of the highest peak power-added efficiencies at millimeter-wave frequencies compared to other PA topologies.

A design concept for a phased-array-fed reflector antenna system intended for millimeter-wave base stations is presented. This concept is motivated by the need for efficient beamforming antenna systems with reduced power consumption as compared to the presently considered fully-populated large-scale MIMO arrays. The main idea is to use a high-gain reflector antenna to maximize the effective isotropic radiated power. That in turn, allows minimizing the number of active antenna elements of the phased-array feed, and hence limit the total supplied power. The proposed reflector antenna system is based on a torus reflector which is illuminated by an offset phased-array feed. We show how to determine the antenna design parameters to achieve the desired cell coverage.

When measuring at higher frequencies, as the wavelength becomes shorter, antenna phase measurements are very sensitive to positioning and alignment errors. The results of a radiation pattern measurement of a WR-28 rectangular open-ended waveguide (OEWG) are shown, and the lack of symmetry in the measured phase indicates a misalignment of the OEWG. A two-parameter misalignment model is used to explain this asymmetry. The measurement data are used to determine the two parameters of the model, and the parameters are subsequently used to correct the phase of the measured radiation pattern, restoring the expected symmetry.

Reflector antennas are utilized in a lot of applications that require a high gain antenna system. Conventionally, the reflector antenna is fed by a single radiating element, making the direction of the beam fixed. Using a focal plane array (FPA) as feeding mechanism, the magnitude and direction of the resulting beam can be controlled electronically. Using an in-house developed tool, the amplitude and phase settings for a 28 GHz active phased array antenna are determined in order to mimic the ideal feeding pattern for a certain reflector. The far-field of the FPA in combination with the reflector antenna is determined for a scan angle of 0° and 3°.

Due to errors in the phase and amplitude of element excitations in an antenna array, the array radiation pattern gets distorted. In order to derive statistical results on this distortion, specifically on determining the probability of exceeding a certain sidelobe level (SLL), it is often assumed that the magnitude of the array amplitude pattern follows a Rician distribution. It is shown that the Rician distribution implies two assumptions, and therefore, a more general Beckmann distribution is proposed to describe the distribution of the magnitude of the array amplitude pattern. Using Monte Carlo simulations, it is shown that the use of a Beckmann distribution outperforms the Rician distribution. Also, the seemingly counterintuitive result that the maximum probability of exceeding a certain SLL, in general, does not have to be at the angle where the highest sidelobe in the error-free case is located, is obtained. Due to this result, the importance of using an angular probability plot is emphasized. Furthermore, a physical explanation for the observed seemingly counterintuitive behavior is given.

The increasing demands for high capacity and ultra-low latency services require to introduce a 5G mobile communications infrastructure based on a centralized radio access network with space division multiplexed optical fronthaul using radio-over-fiber. The transmission of carrier aggregated 5G OFDM signals over an analog radio-over-fiber fronthaul link is experimentally demonstrated. Multi-Gbit/s data rates are achieved in limited bandwidth, with BER below the 25 % overhead FEC limit after millimeter-wave wireless transmission over 2.2 m.

A planar array of closely spaced capacitively coupled antennas over a ground plane can be designed to have a broadband and smooth response, making it an interesting candidate for a low-frequency radio-astronomy instrument. However, surface wave modes propagating over the array plane can seriously degrade the response. We will show the derivation of a necessary condition for which surface wave modes will propagate along a planar array of closely spaced capacitively connected antennas. The derivation will be based upon the transverse resonance method [2] applied to the equivalent circuit of a unit cell of an infinite capacitively connected array. From the necessary condition a simple design consideration can be derived which would prevent the excitation of unwanted surface waves on the structure. Finally, we will show how adding resistive loading in the form of the low-noise amplifiers can dampen the unwanted surface wave effects.

The integration of a differential antenna in mainstream 65 nm CMOS was investigated. A 60 GHz prototype integrated circuit (IC) was developed, including a seal-ring and on-chip calibration structures. Measured results show excellent impedance matching properties over a 10 GHz bandwidth and a moderate antenna gain of -1.5 dBi. However, this is still a significant improvement as compared to state-of-the-art in mainstream CMOS.

This paper presents the first monolithically integrated RF-power harvesting 71 GHz wireless temperature sensor node in 65nm CMOS technology, containing a monopole antenna, a 71 GHz RF power harvesting unit with storage capacitor array, an End-of-Burst monitor, a temperature sensor and an ultra-low-power transmitter at 79 GHz. At 71 GHz, the RF to DC converter achieves a power conversion efficiency of 8% for 5 dBm input power.

The effect of amplitude and phase errors on the radiation properties of phased array can be reduced by using a proper calibration scheme. Based on a brief review of microwave phased-arrays we derived the key requirements for a new anechoic millimeter-wave (mm-wave) antenna set-up which was constructed. The residual measurement errors obtained with this new set-up are low enough for the calibration of low-sidelobe mm-wave phased arrays.