Search

A low‐profile wide‐scan phased array for 28 GHz 5G band operation, based on the current sheet array (CSA) concept, is presented in this work. The array is dual‐polarized with horizontally and vertically polarized dipoles are placed in close proximity to leverage intentional capacitive coupling. A meta‐surface based on fully split rings is printed on the top of the matching layer, contributing to wide‐scan performance. A capacitive metallic plate is placed below the cross‐section formed between orthogonal dipole elements to subdue the in‐band coupled‐loop modes. The design is demonstrated to operate at 26–30 GHz with voltage standing wave ratio (VSWR) <3 for ±60° scanning in principal planes, with a low‐profile 0.26λh. The simulations are validated by measuring an 8 × 8 array prototype, which shows good agreement with the simulated predictions. [ABSTRACT FROM AUTHOR]

ABSTRACT: The PVC/CNT nanocomposite was prepared with commercial poly(vinyl chloride) (PVC) beads and multiwall carbon nanotube (CNT). The comparative values of the electromagnetic interference shielding effectiveness (EMI SE) and electrical conductivity of PVC/CNT nanocomposite in the presence and absence of PVC beads were described. The results showed that the EMI SE values and electrical conductivity values of PVC/CNT nanocomposite had increased compared to those without PVC beads. After the addition of PVC beads, both values of the EMI SE and electrical conductivity had also increased with the increasing of the amount of PVC bead on the PVC/CNT nanocomposite, and the PVC/CNT nanocomposite in the presence of PVC bead showed high EMI SE value (22.6 dB at 4.0 wt% CNT loading in the presence of 70 wt% bead) and high conductivity value (5.31×10−2S cm−1 at 1.0 wt% CNT loading in the presence of 70 wt% bead) at low CNT loading. Thus, PVC beads effectively play a major role in enhancing the EMI SE value and electrical conductivity value of the nanocomposite. To check the bead region and solvent‐dried CNT region in the nanocomposite, morphological studies have been done and morphological studies of the PVC/CNT nanocomposite supported the two‐phase regions in the composite and the selective dispersion of the CNT in the solvent‐dried phase has been clearly observed. [ABSTRACT FROM AUTHOR]

ABSTRACT The polyaniline-polyvinyl alcohol (PANI-PVA) composite conductive coatings were prepared by using PVA as the base material and doping with hydrochloride (HCl), dodecylbenzene sulfonic acid (DBSA), and aminosulfonic acid (NH2SO3H) aqueous solution. The influences of mass ratio between PANI and PVA, acid content, oxidant (ammonium persulfate, APS) content, reaction time, and drying temperature of film on the conductivity of coating film were studied. The result shows that in case the mass percentage of PVA is 40% and the drying temperature of film is 80℃, the conductivity of coating film has the highest conductivity. In case C(HC1) is 0.5 mol⋅L−1, the reaction time is 6 h, and n(APS/An) is 1.0, the maximum conductivity of HCl-PANI-PVA coating film is 1500 S⋅m−1; in case C(DBSA) is 1.0 mol⋅L−1, the reaction time is 8 h, and the n(APS/An) is 2.0, the maximum conductivity of DBSA-PANI-PVA coating film is 710 S⋅m−1; in case C(NH2SO3H) is 1.0 mol⋅L−1, the reaction time is 6 h, and the n(APS/An) is 2.0, the maximum conductivity of NH2SO3H-PANI-PVA coating film is 200 S⋅m−1. Among these PANI-PVA composite conductive coatings, the conductivity of HCl-PANI-PVA coating film is the highest. At the same time, the structure and conductive mechanism of composite materials were characterized and analyzed through infrared and ultraviolet spectrum and scanning electron microscopy. [ABSTRACT FROM AUTHOR]