A defected microstrip structure (DMS) is proposed to reducing the size of a rectangular patch antenna by increasing its electric length, without degrading its performance. To illustrate this advantage, one conventional and one proposed defected patch antenna were developed and measured at 1.77 GHz. The simulated and measured results concerning the radiation patterns and bandwidth of both antennas are very closely related, but the proposed defected antenna achieves 22% of total‐area reduction. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 481–484, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20508

Several papers published by prestigious Journals on Antennas and Microwave Techniques have disseminated misconceptions about total active reflection coefficient (TARC), a meaningful metric to characterize multiple‐input multiple‐output antenna arrays, and the misapprehension has been spread over the years. In this article, an extrapolation to calculate TARC for N‐antennas systems is derived and applied to published results for illustration purposes. Moreover, the inaccurate and correct TARC equations are put in context by means of its physic and mathematical insight, demonstrating the divergence of results when the interport RF isolation is comparable or higher than the port matching. The importance of assessing multiantenna systems using TARC is explained.

Abstract-In the last decades, microwave imaging has been a new area of research due to its many advantages over current imaging systems. Microwave imaging system is used for in-depth inspection of biological tissues. The test provides the identification of morphological changes in these biological tissues, as well as their locations. The emerging Ultra-Wideband (UWB) microwave imaging gives better result with the main advantage of using non-ionizing radiation. In these systems, antennas play a very important role, and as such, their optimization has become a very important topic because the device is placed close to the human body. Thus, many aspects are of great importance in the design of the antennas starting from the material with which it is constructed, its dimensions, operation bandwidth, human body influence on the antenna parameters, short-pulse propagation, etc. Recent research has shown several efforts in improving the electromagnetic sensors used in these systems, either as individual or array elements. In this paper, we provide an overview of the most relevant developments in the field of UWB high directivity sensors used in microwave imaging systems.

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The development of two reduced microstrip slot antennas with a U‐shaped resonant configuration is presented. The additional resonator is located inside the slot and is designed to perform dual band operation, covering the 2.4 GHz and 5.8 GHz WLAN frequency bands. The main goal of the antenna design is to get the optimum size reduction without significant degradation of electrical characteristics compared to a similar antenna reported in literature. The antenna implementation was done using low cost substrates. A size reduction of 84% was got by using a dielectric constant substrate of 10. Simulation and experimental results are presented for both antennas, showing close convergence. Their radiation patterns have quasi‐omnidirectional behavior useful for WLAN applications. Both antennas have small size suitable for mobile applications. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2684–2689, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27187

A new planar inverted-F antenna with a very large bandwidth starting from 817 MHz to 11.5 GHz (VSWR < 3) is proposed as an alternative for high performance mobile phones intended to cover the major part of the mobile phone frequencies worldwide as well as the ultra-wideband (UWB) frequency range. A prototype of the antenna was constructed and the reflection coefficient and radiation patterns were measured to demonstrate an adequate radiation performance. The antenna dimensions of 4 × 2.5 × 0.5 cm 3 are compatible with the requirements imposed by the most recent commercially available smartphones. Besides, the easy construction without a matching network or a complicated geometry is an additional feature that can be reflected in low fabrication cost.