Bloch wave approach to the design of optimally matched non-effective medium composite right/left handed transmission lines

A simple method to design optimally matched composite right-/left-handed transmission lines (CRLH-TLs), based on the computation of the Bloch wave equivalent impedance of the corresponding unit cell circuit is presented. Although the matching of CRLH-TLs that can be considered as effective media is straightforward, it is shown that it is not the case for non-effective medium structures, which are also relevant realisations of this type of metamaterial in particular situations. Since the method does not rely on any assumptions on the parameters of the circuit, it is valid both for effective medium and non-effective medium CRLH-TLs. The reduction of the mismatch obtained with the proposed method also results in an improvement in the insertion loss and phase shift linearity in terms of S-parameters. Finally, we present some experimental validation of the benefits of the method by means of quartz-integrated CRLH-TLs realisations     

Analysis of finite phase arrays of microstrip patches

A method for the analysis of large phased arrays of microstrip patches is presented. It is based on an infinite array approach where the edge effects are taken into account through the convolution with a proper window function. In the first step, a rigorous Green's function corresponding to a finite array of elementary sources is derived. This Green's function is then used to analyze the finite phased array of microstrip patches. Results are shown for the active impedance and element patterns of several arrays, and compared with measurements or, in the case of small arrays, with results obtained by a rigorous element-by-element approach. It is shown that the method, even if developed for the analysis of large arrays, is able to handle small arrays. Indeed, the results obtained are good even for single patches. Although the method has been developed for the microstrip phased array case, the results are general and are valid for any phased array with a rectangular grid     

Analysis of printed array antennas

A simple but efficient analysis tool for printed antenna arrays is presented. It relies on a perturbation approach, which starts from the infinite periodic array assumption to ultimately take into account effects due to finite size, nonperiodicity, double-periodicity in a multilayer case, complex excitation with nonlinear phase shifts between elements, etc. The technique is an approximation, as are most of the array analysis tools. However, it gives good results for arrays presenting a relatively smooth variation of the antenna characteristics between adjacent cells. Results will be shown for several arrays, including nonperiodic and multilayered cases. The method is validated through the comparison with results obtained by a rigorous element-by-element method     

Integrated solar panel antennas

A new antenna which combines solar cells and printed patches is presented. The antenna is designed so as to accommodate the solar cells that provide power to an MMIC amplifier. A 2×4 array is presented, which operates at the frequency of 3.76 GHz and has a bandwidth of 16% and gain up to 30 dBi (active)     

Stainless steel slot antenna with integrated solar cells

A new principle of a solar slot antenna is presented. The slot antenna integrates amorphous silicon solar cells which are directly grown on the ground plane where the slot antenna is cut. To facilitate the deposition of the solar cells, stainless steel was used for the ground plane. The effect on the efficiency of the antenna of this rather unusual choice for the conducting ground plane is also described     

An efficient method to determine Green's functions of atwo-dimensional photonic crystal excited by a line source - thephased-array method

A novel and efficient method to determine Green's functions in photonic crystals (PCs), i.e., the phased-array method (PAM), is presented. The PAM is a combination of the plane-wave method and the array-scanning method, which is both more flexible and computationally faster than the eigenmodes expansion method. A complete derivation of the electric- and magnetic-field Green's functions associated, respectively, with an infinite electric and magnetic current line exciting a two-dimensional PC is given. Although the developments are presented only for a line source, the PAM can be extended to a dipole source. Thus, the PAM represents a promising method for the analysis of printed-circuit elements or antennas on PC materials. Numerical results for the Green's functions are shown for different positions of the source and a discussion about radiation patterns, asymptotic behaviors, and convergence characteristics is proposed     

PCS antenna design: the challenge of miniaturization

PCS (personal communication system) devices have become an important part of everyday life. The pressure to design small, lightweight, and user-friendly mobile-communication devices has increased accordingly, creating the need for optimal antennas for mobile applications. In this paper, we present some basic rules about electrically small antennas, give clues and guidelines about efficient antenna miniaturization, and, finally, show some examples of miniature antennas developed in our laboratory for practical applications