The function of passive wide-angle beam scanning is desired by base station antenna to provide “green” cellular services. In this paper, such function is realized by designing a compact phase-controlled pattern-reconfigurable Dielectric Resonator Antenna (DRA). The proposed DRA has a compact structure with side length of 0.38λc, and excites fundamental TE and TM modes by diverse ports. By assigning phase between diverse ports, E-plane tilted patterns are synthesized with ±66° scan angles. Its pattern-reconfigurable capability makes contributions for increasing array beam scanning angle and minimizing gain fluctuation. A passive four-element array is verified to have an enhanced beam scanning angle of ±81° with gain fluctuation of 1.25 dB. The maximum gain of the scanning beam is located on the off-axis angle of ±66°, and achieves a wide 3 dB scan coverage of ±105°. Good agreements have been shown between measured and simulated results. The proposed phase-controlled pattern reconfigurable DRA and DRA array have impedance bandwidth of 3.33% (2.95-3.05 GHz) for Sub-6GHz wireless system. They enable the wide-angle beam scanning for base station antenna, and provide a cost-effective passive system for “green” communications.

A type of polymeric nanoparticles loading indocyanine green and Pt(II)-porphyrins (ICG-Pt-NPs) is constructed to achieve a synergistic effect of combined photothermal and two-photon activated photodynamic therapy. The nanoparticle core comprises the photosensitizer Pt(II)-porphyrins (PtTFPP), and organic semiconducting polymer (PFO) that acts as a two-photon antenna. Negative ICG molecules, an NIR-absorbing photothermal dye, can be loaded into the positively charged poly-L-lysine (PLL) shell of the polymeric nanoparticles via electrostatic interaction. In these carefully designed ICG-PtTFPP integrated nanoparticles, PtTFPP absorbs the photonic energy transferred by the PFO polymer under two-photon laser excitation at 740 nm to induce photodynamic cancer cell death, while ICG offers nanoparticles a strong photothermal performance under 808 nm laser irradiation. Compared with photodynamic therapy or photothermal therapy alone, the combined therapy had a significantly synergistic effect and improved the therapeutic efficacy with near-infrared irradiation.

This paper reports on a sensor based on multi-element complementary split-ring resonator for the measurement of liquid materials. The resonator consists of three split rings for improved measurement sensitivity. A hole is fabricated at the centre of the rings to accommodate a hollow glass tube, through which the liquid sample can be injected. Electromagnetic simulations demonstrate that both the resonant frequency and quality factor of the sensor vary considerably with the dielectric constant and loss tangent of the liquid sample. The volume ratio between the liquid sample and glass tube is 0.36, yielding great sensitivity in the measured results for high loss liquids. Compared to the design based on rectangular split rings, the proposed ring structure offers 37% larger frequency shifts and 9.1% greater resonant dips. The relationship between dielectric constant, loss tangent, measured quality factor and resonant frequency is derived. Experimental verification is conducted using ethanol solution with different concentrations. The measurement accuracy is calculated to be within 2.8%, and this validates the proposed approach.

Recently gold nanoparticles (GNPs) have been proposed in non-invasive thermal therapies for cancer treatment coupled with radiofrequency (RF) waves. In this work, the dissipation of RF energy by GNPs is systematically investigated both experimentally and theoretically under an EM frequency of 13.56 MHz. To elucidate the impurity effect, purified GNP dispersions are obtained through an ultrasonic-aided method. The result reveals a small bulk temperature increase, i.e., less than one centigrade for impurified samples, and even smaller for purified samples, which contrasts significantly to some earlier publications. The measured dielectric properties of GNP dispersions show a negligible change in the effective conductivities for purified samples, which indicates that the dielectric loss alone does not predict substantial temperature increase of GNPs. Further discussion shows that none of the established theories supports the idea that GNPs can dissipate RF energy significantly.

A dual-band dual-rotational-direction reflective linear-to-circular polarization converter based on metasurface is designed, fabricated, and measured. The unit cell consists of an open ring and a square patch. The open ring creates two resonances, and the square patch is used to improve the axial ratio (AR). It is shown that this design can be working at two frequency bands, i.e., 29.0–41.5 GHz and 52.5–61.5 GHz. Interestingly, it is found that the linearly polarized wave in $x(y)$ -direction can be converted into right(left)-handed circularly polarized wave at the former band, and into left(right)-handed circularly polarized wave at the later band. Compared to other designs in the literature, this design demonstrates 45° angular stability for 3 dB AR over two operational bands. In addition, this design is realized on a single substrate, making it easier to be fabricated. Furthermore, the insertion loss can be as low as 0.5 dB, showing a very low-loss property. Lastly, the unit cell is less than 0.2 wavelength at the lower frequency band. The measured results show good agreement with simulation. Potential applications can be envisaged in dual-band and dual-polarization communication.

Terahertz waves have found wide applications in the biological and medical areas. Since water is one of the most important ingredients in the biological systems, it is necessary to investigate its optical and dielectric properties in the terahertz range. These fundamental physical parameters play an important role in many applications, such as biological imaging and hyperthermia applications, and are temperature dependent. In order to shed more light on the property of temperature dependence, we performed a systematic investigation by changing the temperature of the water sample and using a terahertz time-domain spectrometer. The experimental results show that when the temperature increases from 275 K to 340 K, the refractive index and the complex dielectric constant of water increase noticeable, with the absorption coefficient increased observably. A good agreement is found between experimental data and the double Debye model.