A bow-tie antenna based on a slot configuration in a single metal sheet on top of a very thin flexible substrate is introduced. The antenna is constructed from two slotted right-angle triangles fed by a coplanar waveguide transmission line. The topology is very simple and extremely easy to tune in order to reach the proper characteristics after mounting on a supporting structure. A prototype is designed, fabricated, and characterized experimentally. The tunability is proven by considering both the version in free space and the version for use on a brick wall. Measurements demonstrate good agreement with simulations. Both versions cover the wireless local area network (2.4 and 3.65 GHz) and WiMax (2.3, 2.5, and 3.5 GHz) spectra, with an overall impedance bandwidth of 1.79 GHz (57.7%) and 1.46 GHz (49.7%), respectively. The radiation of the antenna is bidirectional with maximum gains of 6.30 and 5.09 dBi for the free space and brick wall versions, respectively.

This article introduces a new RFID tag antenna designed for operation at 915 MHz. The proposed antenna is electrically small with dimensions (λ₀/15) × (λ₀/15). It features two vivaldi-like apertures flipped with respect to each other around an axis parallel to their slotted edges. Each aperture is loaded with a meander line with multiple loops. The two sides of the proposed antenna are fed via a common slot line that is coupled electromagnetically to a perpendicular microstrip line at the other side of a dielectric substrate. The new antenna are fabricated using printed circuit board technology and the fabricated prototype is experimentally characterized. The optimization and theoretical investigation of the proposed antenna are performed via both HFSS and CST. The two simulators agree very well with each other and with measurements. The characteristics of the new RFID antenna are generally good, such as: small size (22 mm²), low profile (0.8 mm), flexible impedance matching, reasonable impedance bandwidth (8%), omni-directional radiation, low cross-polarization level (−20 dB at broadside), acceptable radiation efficiency (76%), and gain (−0.3 dBi). © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE 23: 639–645, 2013.

A new circularly polarized wire-grid nano-antenna array designed for optical telecommunication applications is proposed in this paper. The array consists of two groups of radiators, which are orthogonal to each other. Each group consists of six aligned radiators connected via nonradiating connectors. A 90° phase shift is achieved by inserting a gap between the feeding coupling rods and the inner radiators of one of the two antenna groups. The antenna is characterized by its high directivity (10.8 dBi) and a wide axial ratio bandwidth, which covers the range from 188.2 to 197.8 THz. The radiation efficiency of the antenna is 82.75% at 193.55 THz with very small variations along its operating bandwidth. Such good radiation characteristics are very attractive for optical communication applications.

This paper introduces a planar antipodal meander line antenna fabricated using RO3003 substrate. The proposed antenna is designed to radiate in the end-fire direction, achieving a maximum measured gain of 10.43 dBi within its working bandwidth, which ranges from 2.24 GHz to 2.7 GHz, covering long-range WLAN/WiMAX applications. A systematic procedure is adopted in the design process to prove its tunability to cover other application requirements in terms of gain and bandwidth. The proposed design steps show that the bandwidth and the gain can independently be controlled by adjusting specific design parameters such as the number of radiators and the scaling factor. The antenna is fine-tuned using sensitivity analysis and parametric study to guarantee optimum operation at the desired bandwidth. Experimental measurements of the fabricated design demonstrate a high degree of correlation with simulations conducted using CST and HFSS. In comparison to other end-fire antennas presented in the literature, the proposed design manifests its capability to provide high gain for WLAN/WiMAX nodes connectivity. The measurements show that the proposed traveling wave antenna exhibits a high radiation efficiency with maximum value of 99.8% at 2.35 GHz. The measured side lobe level is found to be below $$-18$$- 18 dB and $$-20$$- 20 dB at 2.45 GHz along the $$E$$E - and $$H$$H -planes, respectively. Apart from its excellent radiation performance, the antenna is characterized by its low profile and fabrication simplicity.

Metamaterials for refractive index sensing applications have garnered significant attention in recent years. However, achieving an optimal balance between high sensitivity and quality factor, which together determine the Figure of Merit of sensors, necessitates extensive optimization efforts. In this paper, we present the metaheuristic optimization of a refractive index-based plasmonic sensor operating at a wavelength of 1500 nm, which has the potential to open new avenues for applications in biomedical sensing and beyond. Particle Swarm Optimization is utilized to maximize the performance of the proposed infrared metamaterial sensor. The proposed design features two overlapping E-shaped silver patches placed on top of a grounded $$\mathrm {Al_{2}O_{3}}$$Al 2 O 3 substrate. This configuration results in a narrow-band absorption spectrum with peak resonances caused by the confinement of the electric field within the gaps of the E-shaped metallic arms. The metaheuristic optimization process yielded sensor dimensions that achieve a high sensitivity of 834.7 nm/RIU,Q = 865 and a Figure of Merit of 481.34 $$\textrm{RIU}^{-1}$$RIU - 1 , demonstrating outstanding performance in cancer cell detection.