This work aims to build a measurement test bench for wideband mixer EVM characterization at sub-terahertz frequencies. A VNA based setups with two frequency extenders are implemented. While one of the VNA sources can be used as the LO input, the other source will be swept over a frequency grid so that the RF output of the mixer under test will be down converted and read out tone by tone. Then the modulated signals are expected be reconstructed from the frequency domain measurement result, which will be demodulated for EVM characterization. A two-tier calibration method is used to extract the absolute power from the target RF channel. The key performance of the mixer under test, such as conversion loss, image rejection ratio and linearity are measured over an IF bandwidth up to 4GHz. Nevertheless, the major challenge for VNA based EVM measurements are the unhandled phase between the two sources of VNA, preventing the system to reconstruct a stable time domain signal. To solve this problem, an auxiliary phase channel setup is proposed, which can carry the unhandled phase information from one of the VNA source, thus providing a stable phase measurement for EVM measurements. To validate the proposed setups, the adjusted phase is derived from measurement results of the MUT channel and the results from the auxiliary channel. A phase stability of $\pm$5 degrees can be achieved with the proposed setups. Finally, EVM characterization is performed based on the proposed setup. A EVM floor of -30dB is achieved with a 300MHz QPSK signal, the error due to thermal noise is reduced due to the narrow band receiver of the VNA.

This work demonstrates the imaging of (near) diffraction-limited images in the THz domain using a CMOS integrated camera. A Quasi Optical Setup is fabricated, aligned the radiation patterns and losses are characterized.

Front-end Monolithic Microwave Integrated Circuits (MMICs) have recently become commercially available for frequencies above 100 GHz. However, achieving low-loss and broadband interconnections between the antenna and MMICs is challenging for integrated front ends at these frequencies. This thesis presents the characterization of a flip-chip interconnection used for an integrated front end at 150 GHz (G-band) with an on-package leaky-wave dual lens antenna. Two paths for the front-end integration have been proposed. The first path adopts CPW transmission lines on 500 μm-thick fused silica and provides easy assembly and seamless flip-chip capabilities. The second uses microstrip transmission lines on 50 μm-thick fused silica and provides lower transmission line loss but a challenging assembly and flip-chip interconnection. In this thesis, a path toward microstrip and CPW flip-chip interconnections has been outlined at the high millimeter-wave frequencies. Two-port test structures using CPW transmission lines were developed, adopting a double Thru-Reflect-Line calibration and allowing for accurate extracting of the interconnection response. The final interconnection to the MMICs has been realized using a via-less CPW to microstrip transition with high impedance transmission line S11 matching compensation. The simulated S11 and S22 are below -12 dB, Ohmic loss below 0.6 dB, radiation loss below 0.4 dB, and transmission line losses around 0.15 dB/mm.

Millimeter- and submillimeter wave applications, such as point-to-point wireless communications in beyond-5G scenarios, long-range automotive radars and astronomy and astrophysics science cases from space require antennas with high-gain beams that are steerable. At lower (microwave) frequencies, fully sampled phased arrays with thousands of elements have been demonstrated for this purpose. However, above roughly 100 GHz, integrated-circuit technology faces major bottlenecks in terms of size, power efficiency, thermal management and technological immaturity. Consequently, only integrated phased arrays with very few elements have been reported in the literature above 100 GHz. To still achieve the gain and enable beam scanning, mechanically actuated reflectors are now typically employed. However, such solutions are bulky, power-hungry and do not allow rapid beam steering. To overcome these limitations, we propose, analyze, design, fabricate and demonstrate a new antenna architecture in this thesis: the scanning lens phased array. The scanning lens phased array is a compact, low-power and very sparse array of integrated lens antennas that we demonstrate with scanning capabilities up to 25 degrees around broadside. A hybrid electro-mechanical approach to beam steering is employed: the array factor is scanned electronically and the element patterns are steered mechanically. The grating lobes that arise in the array factor due to the array’s sparsity are suppressed by the high directivity of the lens elements. This results in a clean, highgain beam towards the desired scan angle...@en

This thesis is concerned with a first time demonstration of a high frequency scanning lens phased­-array with dynamic steering. Such phased­-array could provide the high gain, wide bandwidth, and steering capability that the next generation of wireless ap­plications requires. The phased-­array development was divided into three distinct parts. First, the electronic phase steering system was discussed and developed, and its stability was characterized over time. Results obtained over 24 hours indicated that the system would be stable to within 6° of high frequency output phase. The drifts in output amplitude remained to within 0.3dB. Next, the lens antenna elements were developed with a novel corrugated leaky ­wave feed that provides very high and broadband aperture efficiency. Antenna measurements have validated its ability to be a very aperture efficient radiator (>80%) with wide bandwidth (1:2). Scanning measurements have shown a 3dB scan loss at around 15°. Finally, the phase steer­ing and antenna elements were combined into a 4×1 array concept. Its behaviour was simulated and indicated again good performance with wide bandwidth (1:2) and high directivity (31.5dBi). Simulated scan loss was approximately 3dB at 20°. The amplitude and phase errors resulted in a SLL standard deviation of 0.63dB. The array prototype is currently awaiting completion of fabrication by DEMO at the TU Delft.