In this paper time modulated nine-ring concentric circular antenna array (TMCCAA) using fitness based novel hybrid adaptive differential evolution with particle swarm optimization (ADEPSO) has been studied. ADEPSO is hybrid of fitness based adaptive differential evolution and particle swarm optimization (PSO). Differential evolution is a simple and robust evolutionary algorithm but sometimes causes instability problem; PSO is also a simple, population based robust evolutionary algorithm but has the problem of sub-optimality. ADEPSO has overcome the above individual disadvantages faced by both the algorithms and is used for the design of TMCCAA. The comparative case studies as Case-1 and Case-2 are made with three control parameters like uniform inter-element spacing in rings, inter-ring radii and the switching “ON” times of rings. The same array radiates at various harmonic frequencies. The first two harmonic frequencies have been considered in this work. The numerical results show Case-2, outperforms Case-1 with respect to better side lobe level (SLL), and more improved directivity. Apart from this, the authors have computed powers radiated at the center/fundamental frequency and the first two sideband frequencies, and dynamic efficiency. It is found that power radiated by any sideband frequency is very less as compared with the power radiated at the center frequency. It has been observed that as the sideband frequency increases, side band level decreases to the greater extent as compared with SLL. The aperture size is a very important constraint for the array, since there is an upper limit for the aperture size of a given array in real-life environment. Hence, in our optimization design, the maximum radius of the concentric ring array is constrained.

To incorporate two different communication standards in a single device, a compact triple-band antenna is proposed in this paper. The proposed antenna is formed by etching an inverted L-shaped slot on the patch with defected ground structure. The antenna is targeted to excite three separate bands first from 2.39–2.51, second from 3.15–3.91, and third from 4.91–6.08 GHz that covers entire Wireless Local Area Network (WLAN) (2.4/5.2/5.8 GHz) and Worldwide Interoperability for Microwave Access (WiMAX) (2.5/3.5/5.5) bands. Thus, the proposed antenna provides feasibility to integrate WLAN and WiMAX communication standards in a single device with good radiation pattern quality. Furthermore, a prototype of the proposed antenna fabricated and measured to validate the design, shows a good agreement between simulated and measured results. The simulation and measurement results show that the designed antenna is capable of operating over the 2.39–2.51 GHz, 3.15–3.91 GHz, and 4.91–6.08 GHz frequency bands while rejecting frequency ranges between these three bands. The proposed antenna offers a compact size of 20 × 30 mm2 as compared with earlier reported papers.

This paper presents a solution to reduce the feed complexity and to improve the total efficiency of X-band compact choke horn antenna with circular polarization and isoflux pattern. This kind of antenna had been designed before by our laboratory for nanosatellite applications, but it required a 4-way divider with phase shifter which generates the insertion losses and therefore a lower realized gain (RG). Among several feeds, a uniform circular helix antenna has been used here, which produces a satisfying feed without too much damage for the axial ratio (AR) and the isoflux pattern over a 400 MHz radiation bandwidth (8.0–8.4 GHz). Theoretical and experimental results show an AR lower than 5 dB and a RG higher than 0 dB at the limit of coverage, i.e. 65° whatever the azimuth angle (φ).

A compact asymmetric coplanar strip fed Sinc shaped monopole antenna suitable for multifrequency operations is proposed for portable wireless devices. The proposed Sinc shaped monopole antenna with truncated half ground plane operates at three frequency bands, 2110–2380, 4180–4600, and 5200–5678 MHz, showing fractional impedance bandwidths of 12, 9, and 8.8%, respectively, suitable for Universal Mobile Telecommunications System, Long Term Evolution handheld devices, Worldwide Interoperability for Microwave Access, Wireless Local Area Network, Hyperlan-2, and aeronautical navigation applications. Proposed antenna shows a dual mode of polarization. Finally a prototype model is developed for a typical configuration and the simulated results are validated experimentally.

A compact dual-frequency antenna with enhanced bandwidth is proposed in this paper. Dual-frequency operation is realized by cutting a slot in the elliptical patch, and bandwidth enhancement is achieved by using a partial ground plane. Compared with the conventional half-wave antenna, the antenna has a compact size of 24 × 20 mm2, which equals to 0.38 λ1 × 0.31 λ1 (λ1, the guided wavelength at the first resonant frequency). The dual-frequency antenna with a partial rectangle ground and a partial arc-shaped ground is investigated for impedance matching. Simulated results indicate that the antenna with a partial arc-shaped ground can obtain a larger bandwidth for two bands than that with a partial rectangle ground. Experimental results show that the antenna with a partial arc-shaped ground can operate in 2.4 and 5 GHz bands, which covers the 2.4, 5.2 and 5.8 GHz for wireless local area network. The impedance bandwidths of two bands are 9.5 and 13.6%, respectively. Also, good radiation performances have been achieved at two bands.

This paper presents a novel technique to design a Rotman lens feeding a wide bandwidth microstrip patch antenna array for 60 GHz radio frequency identification (RFID) applications. The proposed scheme supports both location positioning and increases the communication range through beam forming. The antenna array is designed using λ/4 microstrip transmission lines to support high gain, directivity, and bandwidth. The progressive phase delay using the Rotman lens is realized independently using transmission lines to reduce the complexity of the design and improve the performance parameters. The dummy ports are terminated by λ/4 radial stubs which eliminates the need for via holes and expensive connectors which reduces the fabrication costs.

In this paper, an implantable coplanar waveguide-fed tapered monopole antenna for industrial scientific and medical band (2.4–2.48 GHz) applications is proposed. This proposed design has an overall dimension of 44 × 44 × 0.5 mm3. The designed antenna is made compatible for implantation on human tissues such as skin, fat, or muscles by embedding it on the RT Duroid substrate and the 10 dB return loss bandwidth is 6.12% ranging from 2.35 to 2.5 GHz. This proposed antenna can be significantly used in implantable medical devices and radio frequency (RF), because of its merits such as conformability, flexibility in design and shape, biocompatibility, patient safety, miniaturization, power consumption, etc.

Today's increase of functions, improvement of performances, and cost reductions required on an agile electronically scanned antenna, drive researchers to develop an innovative antennas’ concept in order to deal with the proposed challenge. In this context, this article describes and demonstrates an experimental prototype to show the reliability and efficiency of the electromagnetic band gap (EBG) matrix antenna theoretical aspect, for beam forming and beam steering applications. The originality of this work is the antenna itself which constitutes the subject of an accepted national and international patent. In fact, the proposed antenna is based on the equivalent radiating surface approach and used special EBG antennas called “pixels” to overcome some of the array approach defects. The antenna has demonstrated different electromagnetic behaviors, such as low mutual coupling, high gain preservation for high scanning angles values, etc.

In this paper, we study the influence of the radius of a cylindrical supporting structure on radiation properties of a conformal millimeter-wave antenna array. Bent antenna array structures on cylindrical surfaces may have important applications in future mobile devices. Small radii may be needed if the antenna is printed on the edges of mobile devices and in items which human beings are wearing, such as wrist watches, bracelets, and rings. The antenna under study consists of four linear series-fed arrays of four patch elements and is operating at 58.8 GHz with linear polarization. The antenna array is fabricated on polytetrafluoroethylene substrate with thickness of 127 µm due to its good plasticity properties, and low losses. Results for both planar and conformal antenna arrays show rather good agreement between simulation and measurements. The results show that conformal antenna structures allow achieving large angular coverage and may allow beam-steering implementations if switches are used to select between different arrays around a cylindrical supporting structure.