Laura Pometcu’s research while affiliated with Atomic Energy and Alternative Energies Commission and other places

... During the measurement campaign, the Rx positioner executed an x-y-z spatial grid for each Tx position. Two 20 dBi gain, linearly polarized horn antennas were used in the experiment [81]. An external laptop and ethernet cables were used to control the two positions and VNA acquisitions. ...

Reference:

Recent trends and future directions in millimeter wave massive MIMO channel characterization at 30/60/140 GHz: a review

... [19][20][21][22][23][24][25][26][27][28][29][30][31]. However, these studies do not necessarily offer sufficient insights for designing a sub-THz WPAN system operating in a personal desk area, largely due to discrepancies in measurement scenarios. ...

Reference:

105 GHz Multipath Propagation Measurement and Comparison with 60 GHz in Office Desk Environment for Ultra-High Speed Sub-THz WPAN Systems

... Nonetheless, all the work presented above is based on the assumption that the channel is dominated by its LoS contribution. Even if this assumption has been validated by recent studies [46][47][48][49], some scenarios with a second strong resolvable path can exist such as indoor environment, vehicular communications with the ground rebound. In such cases, our work cannot be trivially extended because the propagation channels become frequency selective. ...

Reference:

Analysis of Gaussian phase noise effects in DFT-s-OFDM systems for sub-THz transmissions

... A simple correction factor for close-distance transmission between two identical, electrically short dipoles can be found [38] as follows: ...

Reference:

A Full Calibration Approach on a Drone-Borne Platform for HF Antenna Measurements in Smart Grid Energy Facilities

... In this study, CST Microwave Studio (CST-MWS) was used to design PMA and base layer. It is one of the popular software to analyse microwave absorber [27,28]. A RH hollow PMA was designed in [14], where the measured dielectric properties are defined in using CST-MWS to optimise the absorber's geometry. ...

Reference:

Enhanced Microwave Absorption of Rice Husk-Based Pyramidal Microwave Absorber with different Lossy Base Layer

... The dielectric characterization of the composites was carried out, in an anechoic chamber, using a quasi-monostatic configuration with two horn antennas operating in the 2− 18 GHz range. The target (samples of 15 × 15 × 6 cm 3 ) was placed at a 2.6 m distance from the antennas, ensuring the far field condition, as explained in the work of Pometcu et al. [41]. The complex permittivity (ε * = ε ' − jε '' ) of the material is extracted from the measured reflection coefficients using Fenner et al. method [42]; dielectric losses, which indicate the overall microwave attenuation inside the composite material, are defined by tanδ = ε'' ε' . ...

Reference:

Ultra-porous and lightweight microwave absorber based on epoxy foam loaded with long carbon fibers

... It can be found from previous studies that the simple and practical method to enhance the EMW attenuation capability and impedance matching of cement-based materials is to add lossy additives and wave-transparent aggregates. The conductive and magnetic fillers, such as carbon black (CB) [7][8][9], carbon nanotubes (CNT) [10][11][12], carbon fiber [13,14], ferrites [15,16], steel fiber [17,18], metal particles [19][20][21], metallic oxide [22,23], etc., can convert electromagnetic (EM) energy into heat energy under the alternating EM fields through resistance loss, dielectric loss, and magnetic loss. Wave-transparent media, such as fly ash [24,25], silica fume [26,27], expanded polystyrene [28][29][30], expanded perlites [31], glass microspheres [32], etc., can guide EMWs into the interior of the material without losing EM energy. ...

Reference:

Electromagnetic wave absorbing properties of pyramidal engineered cement mortar containing carbon black

... 3 In the context of 5G ACs, SPA struggles to provide adequate absorption at extremely high frequencies, particularly in the mm-wave range due to its inherent physical properties and the characteristics of these frequencies. 22 The specialized designs needed for sufficient broadband performance can increase construction and maintenance costs. 1 Additionally, the required thickness of SPA can result in space constraints within the chamber. Moreover, SPA has narrow operating angles and can be susceptible to interference from nearby reflective surfaces. ...

Reference:

The prospect of using hollow pyramidal microwave absorbers for 5G anechoic chamber applications: A review

... Having a well-constructed anechoic chamber suitable for RCS measurements is challenging for many laboratories. In fact, some studies related to RCS inevitably present measurement results from nonanechoic chambers [19], [20], [21], [22], [23]. However, these studies only measure simple TUTs, such as plates, without addressing the validity of their setups. ...

Reference:

Ultra-Low-Cost Radar Cross Section Measurement and Validation Method Using a 3D-Printed Scale Model in a Non-Anechoic Chamber Environment

... This flexibility is revealed to be restrictive in the development of complex geometries, necessary for the optimization of the absorption performance of the absorbers. 57 In order to decrease the flexibility and thus, optimizing the cutting process, we propose to replace the polyurethane foam by the epoxy foam matrix that presents better mechanical properties. Indeed, compressive strength of epoxy foams is 1000 to 10,000 times higher than that of polyurethane foams. ...

Reference:

Carbon Fibers Loaded Composites for Microwave Absorbing Application: Effect of Fiber Length and Dispersion Process on Dielectric Properties