This research work presents a planar compact electromagnetic bandgap (EBG) structure with the potential to reduce the mutual coupling between the elements of a microstrip antenna array. The proposed structure is investigated at 5.59 GHz, which is the centre frequency of the wireless local area network band. To achieve the highest radiation performance for microstrip antenna arrays, with minimal inter‐element spacing and mutual coupling, different unit cell arrangements were considered along with two adjacent patch elements. The simulations and measurement results for the proposed arrangements indicate that the mutual coupling tends to diminish significantly. For instance, when adjacent patches are spaced by 0.4λ, the mutual coupling improves by ∼25 dB. For the particular spacing of 0.4λ, it is favourably observed that the proposed EBG cells can also improve the antenna gain by ∼2.5 dB. Such improvements can be attributed to the compactness of the cells (∼λ/8 × λ/10) and their remarkable ability to suppress the surface waves.

Abstract-The transmission line transfer matrix method (TLTMM)is presented for the analysis of multilayer electric structures as frequency selective surfaces (FSS), whereby the reflection, transmission and absorption coefficients, field distribution and power flow may be computed inside and outside of the layers. The TLTMM formulation may be developed for any arbitrary angle of incidence, any polarization (linear TE or TM, circular, elliptical) of the incident plane wave, at any frequency of operation (microwave, millimeter wave, optical), any number dielectric layers with arbitrary thicknesses, lossless or low loss dielectric media, inclusion of dispersion relation, etc. A general formulation is given for both the TE and TM polarization of the incident wave. Several practical situations are treated by TLTMM namely, anti-reflection coatings, high reflection surfaces, computation of the axial ratio of the reflected and transmitted plane waves, distributed brag reflector (DBR), a narrow band filter consisting of two Fabry-Perot resonators, cantor superlattices in optics, field distribution and power flow for a multilayer structure. Consequently, it is verified that TLTMM is capable of analysis a variety of practical multilayer dielectric structures.

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The reflection and transmission coefficients of multilayer structures are computed by the Transmission Line Transfer Matrix Method (TLTMM) and it is shown that metamaterials (MTMs) act as frequency selective surfaces (FSSs). Several examples of multilayer structures are analyzed, which are composed of combination of common materials and MTMs with dispersion relations. Interesting and uncommon behaviors are observed for MTMs. Novel applications are treated by TLTMM and a matrix method. The physical realizability of MTM structures and their optimum design are also described.

A transparent advanced electromagnetic structure is designed to be used in real‐world Wi‐Fi shielding applications. Concentric square loops as frequency selective surfaces (FSSs) are analytically presented with the Pyrex glass substrate based on the equivalent electric circuit model. The designed FSS window suppresses signals at both 2.5 and 5 GHz bands, and reflects back to the indoor medium. Visible light transmittance of the studied window is achieved as 87%. Accordingly, other electromagnetic communication links can transfer through the designed filter such as cell phone, and radio. The dependency of the proposed window to polarization and angular variations is examined numerically, which shows stable frequency response at 2.5 GHz and an acceptable one for 5 GHz. As a figure of merit, the proposed structure is a double glazed window with potential application for smart, secure, and energy‐saving buildings. Also, practical considerations regarding the deployment of FSS on window glass and the separation distance between the glass layers have been investigated. A prototype of the proposed design is fabricated and measured that a good agreement between measurement and simulation is demonstrated. Therefore, parametric circuit model analysis, deployment of transparent substrate, thin metallic parts on one layer, secure indoor communications, and energy‐saving are some of the advantages of the proposed window.