Abstract
Stars orbiting the compact radio source Sgr A* in the Galactic Center serve as precision probes of the gravitational field around the closest massive black hole. In addition to adaptive optics-assisted astrometry (with NACO/VLT) and spectroscopy (with SINFONI/VLT, NIRC2/Keck and GNIRS/Gemini) over three decades, we have obtained 30-100 mu as astrometry since 2017 with the four-telescope interferometric beam combiner GRAVITY/VLTI, capable of reaching a sensitivity of m(K)=20 when combining data from one night. We present the simultaneous detection of several stars within the diffraction limit of a single telescope, illustrating the power of interferometry in the field. The new data for the stars S2, S29, S38, and S55 yield significant accelerations between March and July 2021, as these stars pass the pericenters of their orbits between 2018 and 2023. This allows for a high-precision determination of the gravitational potential around Sgr A*. Our data are in excellent agreement with general relativity orbits around a single central point mass, M-center dot=4.30 x 10(6)M(circle dot), with a precision of about +/- 0.25%. We improve the significance of our detection of the Schwarzschild precession in the S2 orbit to 7 sigma. Assuming plausible density profiles, the extended mass component inside the S2 apocenter (approximate to 0.23 '' or 2.4 x 10(4)R(S)) must be less than or similar to 3000M(circle dot)(1 sigma), or less than or similar to 0.1% of M-center dot. Adding the enclosed mass determinations from 13 stars orbiting Sgr A* at larger radii, the innermost radius at which the excess mass beyond Sgr A* is tentatively seen is r approximate to 2.5 ''>= 10x the apocenter of S2. This is in full harmony with the stellar mass distribution (including stellar-mass black holes) obtained from the spatially resolved luminosity function.

Abstract
Aerial networks, composed of Unmanned Aerial Vehicles (UAVs) acting as Wi-Fi access points or cellular base stations, are emerging as an interesting solution to provide on-demand wireless connectivity to users, when there is no network infrastructure available, or to enhance the network capacity. This article proposes a traffic aware topology control solution for aerial networks that holistically combines the placement of UAVs with a predictive and centralized routing protocol. The synergy created by the combination of the UAV placement and routing solutions allows the aerial network to seamlessly update its topology according to the users' traffic demand, whilst minimizing the disruption caused by the movement of the UAVs. As a result, the Quality of Service (QoS) provided to the users is improved. The components of the proposed solution are described and evaluated in this article by means of simulation and an experimental testbed. The results show that the QoS provided to the users is significantly improved when compared to the corresponding baseline solutions.

Abstract
Today, wireless networks are operating in increasingly complex environments, impacting the evaluation and validation of new networking solutions. Simulation, although fully controllable and easily reproducible, depends on simplified physical layer and channel models, which often produce optimistic results. Experimentation is also influenced by external random phenomena and limited testbed scale and availability, resulting in hardly repeatable and reproducible results. Previously, we have proposed the Trace-based Simulation (TS) approach to address the problem. TS uses traces of radio link quality and position of nodes to accurately reproduce past experiments in ns-3. Yet, in its current version, TS is not compatible with scenarios where Multiple-In-Multiple-Out (MIMO) is used. This is especially relevant since ns-3 assumes perfectly independent MIMO radio streams. In this paper, we introduce the Trace-based Wi-Fi Station Manager Model, which is capable of reproducing the Rate Adaptation of past Wi-Fi experiments, including the number of effective radio streams used. To validate the proposed model, the network throughput was measured in different experiments performed in the w-iLab.t testbed, considering Single-In-Single-Out (SISO) and MIMO operation using IEEE 802.11a/n/ac standards. The experimental results were then compared with the network throughput achieved using the improved TS and Pure Simulation (PS) approaches, validating the new proposed model and confirming its relevance to reproduce experiments previously executed in real environments.

Abstract
Featured Application Short-range millimetre wave communications. The design of a uniformly spaced 1 x 4 linear antenna array using epitaxial layers of benzocyclobutene over an InP substrate is demonstrated. The array elements are conjugately matched with a uni-travelling carrier photodiode at the input. The phased array is optimised to counteract mutual coupling effects by introducing metal strips with isolated ground planes for each radiating element. The proposed antenna array can provide a gain of 10 dBi with a gain variation of +/- 3 dB. The array operates over a bandwidth of 10 GHz (295-305 GHz) with a wide scanning angle of 100 degrees in the broadside.

Abstract
In this paper we present the latest results on the design, fabrication and test of stand-alone photonic devices devoted to ultra-high bandwidth wireless access networks operating near the Terahertz (THz) band. We review the sub-THz photonics-based technology devices developed as part of the TERAPOD project, comprising the monolithically integrated Silicon Nitride photonic integrated circuit for phase distribution, the 1x4 array of integrated Uni-Travelling Carrier Photo-Diodes (UTC-PDs) and the radiative design of the high-frequency four element linear patch antenna array based on Benzocyclobutene (BCB) layers. We also report the suitability to assemble all those components in a robust small-form factor hybrid package.

Abstract
An in-plane resonant cavity-assisted coplanar Housing waveguide (CPW) to rectangular waveguide (WG) transition is Cavity Bo). realized over an Indium Phosphide (InP) substrate with a thickness of 205 gm using a monopole radiating element. The simulated back-to-back (B2B) structure provides a bandwidth 16 GHz (288 - 304 GHz) with a return loss of 10 dB and insertion loss of 0.6 dB.