This communication presents a reconfigurable antenna capable of independently reconfiguring the operating frequency, radiation pattern and polarization A switched grid of small metallic patches, known as pixel surface, is used as a parasitic layer to provide reconfiguration capabilities to existing antennas acting as driven element The parasitic pixel layer presents advantages such as low profile, integrability and cost-effective fabrication A fully operational prototype has been designed, fabricated and its compound reconfiguration capabilities have been characterized The prototype combines a patch antenna and a parasitic pixel surface consisting of 6 $\,\times\,$ 6 pixels, with an overall size of $06 \lambda \times 06 \lambda$ and 60 PIN-diode switches The antenna simultaneously tunes its operation frequency over a 25% frequency range, steers the radiation beam over ${\pm 30^\circ}$ in E and H-planes, and switches between four different polarizations ( ${\mathhat{\rm x}},$ ${\mathhat{\rm y}}$ , LHCP, RHCP) The average antenna gain among the different parameter combinations is 4 dB, reaching 6–7 dB for the most advantageous combinations The distance between the driven and the parasitic layers determines the tradeoff between frequency tuning range (12% to 25%) and radiation efficiency (45% to 55%)

Frequency, radiation pattern and polarization reconfigurable antenna using a parasitic pixel layer

The paper proposes an ultra-narrow band graphene refractive index sensor, consisting of a patterned graphene layer on the top, a dielectric layer of SiO2 in the middle, and a bottom Au layer. The absorption sensor achieves the absorption efficiency of 99.41% and 99.22% at 5.664 THz and 8.062 THz, with the absorption bandwidths 0.0171 THz and 0.0152 THz, respectively. Compared with noble metal absorbers, our graphene absorber can achieve tunability by adjusting the Fermi level and relaxation time of the graphene layer with the geometry of the absorber unchanged, which greatly saves the manufacturing cost. The results show that the sensor has the properties of polarization-independence and large-angle insensitivity due to the symmetric structure. In addition, the practical application of testing the content of hemoglobin biomolecules was conducted, the frequency of first resonance mode shows a shift of 0.017 THz, and the second resonance mode has a shift of 0.016 THz, demonstrating the good frequency sensitivity of our sensor. The S (sensitivities) of the sensor were calculated at 875 GHz/RIU and 775 GHz/RIU, and quality factors FOM (Figure of Merit) are 26.51 and 18.90, respectively; and the minimum limit of detection is 0.04. By comparing with previous similar sensors, our sensor has better sensing performance, which can be applied to photon detection in the terahertz band, biochemical sensing, and other fields.

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Design of Ultra-Narrow Band Graphene Refractive Index Sensor

Recently hybridized monolayers consisting of hexagonal boron nitride (h-BN) phases inside graphene layer have been synthesized and shown to be an effective way of opening band gap in graphene monolayers [1]. In this letter, we report an ab initio density functional theory (DFT)- based study of h-BN domain size effect on the elastic properties of graphene/boron nitride hybrid monolayers (h-BNC). We found both inplane stiffness and longitudinal sound velocity of h-BNC linearly decrease with h-BN concentration.

Elastic Properties of Hybrid Graphene/Boron Nitride Monolayer

Graphene-based highly efficient and broadband solar absorber

Metasurface based broadband solar absorber

The presented manuscript represents a miniaturized microstrip patch antenna with frequency and pattern reconfigurability. Three modes are analyzed based upon switching actions of two PIN diodes to achieve tunability. Low profile material FR-4 is used for the fabrication. The analysis is carried out in terms of tunability, reflectance response, resonance frequency, electric field, and bandwidth. The proposed structure provides tunability for the two bands. The proposed design provides the maximum tunability of 340 MHz, the bandwidth of 700 MHz, reflectance response of − 40.38 dB, an electric field of 4234.9 V/m, and beam tilting capability of 30°, − 40°, + 35°, − 90°, and 120°. Simulation and fabrication are carried out for the verification. The optimization of design is carried out by varying the dimensions of the three parameters. The comparison is also carried with previously published work. The proposed design can be used for multiband applications in the S and C bands.

Vishal Sorathiya

Papers

Metasurface based broadband solar absorber

Design and Verification of Novel Low-Profile Miniaturized Pattern and Frequency Tunable Microstrip Patch Antenna Using Two PIN Diodes

Dispersion compensation FBG with optical quadrature phase shift keying (OQPSK) modulation scheme for high system capacity

Free space and wired optics communication systems performance improvement for short-range applications with the signal power optimization

Wide band fiber systems and long transmission applications based on optimum optical fiber amplifiers lengths