Conventional multiband antennas suffer from strong interactions among different operating frequencies, complex configurations, low bandwidth, and reduced efficiencies. A design concept for a multibeam multiband antenna in wireless devices is proposed in this paper. The design concept provides a promising approach to augment transmission and reception. The principle of design involves a primary radiating element embedded in a triplate conformation which excites a passive array of multiple frequency secondary radiators, forming a frequency selective structure in triplate (FSST). The higher order mode behavior of the parent antenna characterizes the design of FSST placed in its nearfield. The mathematical modeling and analysis of the design methodology is also presented. As proof of concept, the proposed design methodology is validated with simulations and experiments at four unlicensed communication bands and the results are compared.

In mathematical definition, a fractal is a self-similar subset of Euclidean space whose fractal dimension strictly exceeds its topological dimension which in turn involves a recursive generating methodology that results in contours with infinitely intricate fine structures. Fractal geometry has been used to model complex natural objects such as clouds coastlines, etc., that has space-filling properties. In the past years, several groups of scientists around the globe tried to implement the structure of fractal geometry for applications in the field of electromagnetism, which led to the development of new innovative antenna configurations called “fractal antennas” which is primarily focused in fractal antenna elements, and fractal antenna arrays. It has been demonstrated that by exploiting the recursive nature of fractals, several marvellous kinds of properties can be observed in antennas and arrays. The primary focus of this article is to provide a compressed overview of the developments in fractal-shaped antennas as well as arrays over the last few decades where the most prominent contributions mostly from IEEE journals have been highlighted. The open intention of this review work is to show an encouraging path to antenna researchers for its advancement using fractal geometries.

This literature presents a comprehensive, technical review of circularly polarized (CP) antennas for different applications in wireless communication, emphasizing on the recent developments in the concerned research. The article also presents a comparative study of various works reported in the open literature, with an aim to highlight the contribution of CP antenna systems in the chronological development of the wireless communication technology. The primary motive of this review is to (a) highlight the methodologies used by different researchers to portray and analyze the different aspects in which CP antennas find their applications in modern-day wireless communication, (b) provide a practical viewpoint of the future scope of the study, based upon the past and present state-of-art research trends and (c) provide a conceptual and technical support to present-day antenna designers to help the process of furtherance of innovation and multiple system integration. In conclusion, the article also throws some light upon the future scope of research in the vast domain of CP antenna applications.

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.

The design and fabrication of a wide-band programmable radio frequency (RF) feed network is proposed. It is designed to cover a wide band from 2.5 to 6 GHz over two separate branches. The feed network is simulated and fabricated on an FR-4 substrate with 0.8 mm thickness. Good matching between simulation and measurement results is achieved. The measured amplitude resolution was 0.5 dB with a maximum error of 0.22 dB. The measured phase resolution was approximately 5.6° with 1° maximum error. This design is a generic one that can be used in any kind of RF or antenna systems.

This paper focuses on multi-radio front-end transmitter, a function implied by cognitive radio (0.5–6 GHz). S and C bands standards (wireless local and metropolitan area networks) present a challenge, due to the signal modulation schemes (orthogonal frequency division multiplex (OFDM)/WCDMA, wideband code division multiple access) dynamic (tens of dBs), driving us to a mandatory transmitter linearization. The idea is to provide frequency, flexibility, and average power control of a multi-radio high-efficiency front end for such signals (polar/envelope elimination and restoration (EER) structure). The study implies antennas design and average power control demonstration. Based on a switched mode power amplifier (PA), a discrete detuning is possible to adapt the PA at both “WiMAX” and “Wifi5” frequencies. This architecture amplifies signals with amplitude information. This is coded here by the ΣΔ/PWM (pulse width modulation) technique, to present a constant envelope signal. The amplitude information is restored by a pass-band radio frequency (RF) filter. The antenna can be designed with a notch, to reduce the filtering constraints (selectivity and standards coexistences) and to help in the restoration of amplitude information. Average power control is illustrated by voltage supply variation and results are a possible dynamic of 9.5 dB. To complete the analysis, the simulation of the propagation channel, including antennas, with CST (free space, line of sight) is imported under AGILENT-ADS.

This paper deals with a robust RFSID (Radio Frequency Self IDentification) system for road-to-car communications. The RFSID-based system operates in Ku-band and consists of a fixed transmitter, located at the road side, and of a receiver unit placed on the moving target, i.e. a car in its first proposed application. A slotted waveguide antenna array is used to illuminate the moving object at the desired position, whereas a four-patch array antenna is adopted at the receiver side. Both the antennas have been designed using numerical simulations based on a Finite Difference Time Domain (FDTD) algorithm. When the moving object crosses the antenna beam a triggering pulse is generated by the receiver; such a pulse can be used to reset or update the electronics aboard the vehicle and to log specific information coming from location-based systems (LBSs), into the car equipments. A digital transmission of gold sequences and a post-processing unit have been exploited so far to increase the robustness and the accuracy of the system. At this stage of the development the system benefit of extensive field tests, being adopted for some years by many top Formula 1 racing teams as a lap trigger system, used to reset the on-board electronics when the car crosses either the finishing line and peculiar path reference points. The temporal accuracy exhibited is better than 1 ms with a coverage of about 90 m.