Near-Field Calibration Methods for Integrated Analog Beamforming Arrays and Focal Plane Array Feeds

Active millimeter-wave beamforming arrays and focal plane array antennas require extensive calibration to compensate for impairments, such as phase and gain variations between elements, as well as unintended coupling between changes in gain and phase. When far-field calibration methods are used for calibrating focal plane array antennas, the required size of the anechoic chamber is exceedingly large. For this reason, a near-field calibration method for millimeter-wave analog beamforming array antennas and focal plane array antennas is proposed. Nonidealities of the beamformer integrated circuits with vector modulators are taken into consideration, and a way to reduce the measurement set for vector modulators with high resolution is proposed. This method is both practical and achieves a good calibration as evidenced by measurements of the radiation patterns, and it is suitable for use in an automated factory calibration setup. The important trade-off between the radiated power and side-lobe level is highlighted.</p

A System Performance Based Comparison of Sparse Regular and Irregular Antenna Arrays for Millimeter-Wave Multi-User MIMO Base Stations

A system-level study was conducted that evaluated the system performance of various dense and sparse antenna array configurations for application in millimeter-wave multi-user multiple-input multiple-output base stations. The performance was evaluated by investigating the probability that a user experiences an outage when a zero-forcing pre-coder is used in a random line of sight scenario. This paper shows that the outage probability significantly decreased when irregular sparse arrays were used rather than regular sparse or regular dense arrays. A re-configurable linear array was designed and realized as a demonstrator. It used 3D-printed aluminum box horn antenna elements that had wide scanning range in the azimuthal plane and a small scanning range in the elevation plane. For the demonstrator, it was shown that the outage probability was reduced from 3.85% to 0.64% by moving from a sparse regularly spaced array to a sparse randomly spaced array. This amounted to an improvement of a factor of six. The sparse topology allowed for the usage of large antenna elements that had an increased gain and still achieved wide-angle scanning, while reducing mutual coupling to a minimu

Beam Shape Reconfigurability of Wide-Scan Focal Plane Array Antennas

In this contribution we investigate the flexibility of wide-scan focal plane array antennas at mmWave. Based on measurement data, it is shown that highly directive beams can be generated, as well as wide beams with increased transmission power which are useful in stormy conditions where the rain attenuates the signal and the antenna tower twists and sways due to the wind. In addition, it is shown that sum and difference beams can be generated which can be used for radar sensing applications. The directivity is between 31.4dBi and 37.2dBi depending on the beam type, with a relative transmission power between 10.5dB and 18.1dB, compared to the maximum transmission power of a single antenna element

Radiated Spectrum of Focal Plane Array Antennas with LINCA Array Feeds

In this contribution, radiation pattern measurements of a focal plane array antenna are combined with simulated outphasing waveforms to investigate the radiated spectrum. The recombination of the outphasing signals takes place in free-space (LINCA). The dynamic range is calculated and it is discussed whether the spectral masks would be violated with this system. A dynamic range of 24.1dB can be achieved, but the radiated out-of-band spectral components are not mitigated by the directive nature of the reflector

E-band Point-to-Multipoint Antennas Based On Wide-Scan Focal Plane Arrays

An antenna-system concept is explored where a wide-scan focal plane array antenna is used for point-to-multipoint communications at E-band. As a preliminary study the directivity is investigated for a beam scanning to boresight for several array sizes and inter-element spacings and the azimuthal cuts are compared to the ETSI class-III radiation pattern envelope

Package Thickness Investigation of the U-Slot Patch Antenna for Beyond-5G Antenna-in-Package Applications

The U-slot patch antenna is explored as broadband antenna solution for a multi-layer interconnect antenna-in-package (AiP) technology for beyond-5G and 6G phased array applications. An initial design method is used to investigate the bandwidth response of the U-slot patch antenna for different package thicknesses. Simulation results show that a bandwidth larger than 30% can be achieved for package thicknesses between 0.06λ0 and 0.10λ0 with relative permittivity of 2.81 at a center frequency of 28 GHz. A decreased package thickness below 0.06λ0 and restrictions on the line spacing of the package technology results in decreased bandwidth due to the increase of the Q-factor of the antenna and a smaller separation of the resonance peaks

Over-The-Air Noise-Figure Measurements of Active Integrated Antennas at W-Band

This paper applies an existing method for estimating the system gain and noise figure of active integrated antennas to W-band frequencies. The method uses a reverberation chamber as a wireless noise source, where the ENR can be tuned. Measurements, including different calibration steps, are performed to obtain the noise figure and system gain of a horn antenna connected to a low-noise amplifier as a proof of concept for measuring an integrated antenna. The preliminary measured results are within 1.0 dB of the datasheet value for part of the measured frequency span. Limits of this method are demonstrated through the measurement campaign and recommendations for improvement are provided

Total Radiated Power Measurement at 100 GHz in a Reverberation Chamber

In this work, a proof-of-concept of a total-radiated-power (TRP) measurement in a mm-wave reverberation chamber at 100 GHz is shown for the first time. A signal generator connected to a horn antenna was used as a device under test, to be able to have a reference value. The over-the-air measured TRP is within 0.45 dB of the reference value, where the expanded uncertainty is 0.53 dB. This shows a proof-of-concept of the suitability of this chamber for TRP measurements of 6G integrated devices, paving the way for measurements of antennain-package or antenna-on-chip applications