Bandwidth enhancement of dual-band bi-directional microstrip antenna using complementary split ring resonator with defected structure for 3/5 GHz applications

<span>This paper presents a bandwidth enhancement of a dual-band bi-directional rectangular microstrip patch antenna. The novelty of this work lies in the modification of conventional rectangular microstip patch antenna by using the combination of two techniques: a complementary split ring resonator (CSRR) and a defected patch structure (DPS). The structure of antenna was studied and investigated via computer </span><span>simulation technology (CST). The dimension and position of CSRR on the ground plane was optimized to achieve dual bandwidth and bi-directional radiation pattern characteristics. In addition, the bandwidths were enhanced by defecting suitable shape incorporated in the microstrip patch. A prototype with overall dimension of 70.45×63.73 mm² has been fabricated on FR-4 substrate. To verify the proposed design, the impedance bandwidth, gain, and radiation patterns were carried out in measurements. The measured impedance bandwidths were respectively 560 MHz (3.08-3.64 GHz) and 950 GHz (4.64-5.59 GHz) while the measured gains of each bandwidth were respectively 4.28 dBi and 4.63 dBi. The measured radiation patterns were in good agreement with simulated ones. The proposed antenna achieves wide dual bandwidth and bi-directional radiation patterns performances. Consequently, it is a promising candidate for Wi-Fi or 5G communications in specific areas such as tunnel, corridor, or transit and rail.</span>

Radiation patterns of patch antennas on coated conducting cylinders

The development of the Internet of Things and communication systems of the fifth generation leads to the need to place many antenna elements in a limited volume. Therefore, wearable electronics antennas are often located directly on the device body. Such surfaces can often be thought of as a conducting cylinder covered with a dielectric material. The task of analysing the radiation patterns of antennas located on such surfaces becomes urgent. This paper shows a method for analysing antenna directivity diagrams using the Green’s functions method of cylindrical layered media. This method allows to obtain in an analytical form the expressions for the analysis of such structures, which makes it possible to reduce the cost of computer time in modelling. The presented results show what kind of distortions are introduced into the radiation pattern of antennas located on a cylinder compared to an antenna located on a flat surface.

Flat UWB antenna with optimized ground plate

The design of a broadband antenna based on a combination of electric and magnetic emitters is proposed. Antenna size ratios are proposed that provide a wide operating frequency band. The results of numerical modeling of the standing wave ratio and radiation patterns for a particular case with a matching range from 13 GHz to 27 GHz are presented.

Smartphone Model Fingerprinting using WiFi Radiation Patterns

This paper aims to demonstrate the feasibility of our proposed method for fingerprinting different classes of wireless devices. Our method relies on the observation that different device types, or indeed different models of the same type, have different wireless radiation patterns. We show in detail how a small set of stationary receivers can measure the radiation pattern of a transmitting device in a completely passive manner. As the observed device moves, our method can gather enough data to characterize the shape of the radiation pattern, which can be used to determine the type of the transmitting device from a database of patterns. We demonstrate that the patterns produced by different models of smartphones are easily different enough to be identified. Our measurements are repeatably measurable using RSS with commercial-off-theshelf hardware. We then use simulations to show the success of our method as a classifier.

Novel Compact Design and Investigation of a Super Wideband Millimeter Wave Antenna for Body-Centric Communications

This paper presents a novel design for a multiple band millimeter wave antenna with a wide active region in the extremely high frequency (EHF) range. The antenna's performance was tested at three evenly separated frequencies: 60 GHz within the V-band region, 80 GHz within the E-band region, and 100 GHz. Simulation exhibits satisfactory results in terms of gain and efficiency, although the efficiency falling tendency for higher frequency persists. As millimeter wave antennas have miniature-like dimensions and low penetration depth into human body layers, the performance of these antennas is less disturbed by the presence of a human body, making them ideal for body-centric wireless communication (BCWC) applications. Thus, a human body model was created virtually with the necessary property data. Simulations are repeated at the same frequencies as before, with the antenna kept close to the constructed human body model. The results were promising as the gains found increased radiation patterns and return loss curves remained almost identical, except some efficiencies that were considered. Some H-plane radiation patterns are changed by the presence of a human body. Although all three frequencies present satisfactory results, 60 GHz is found to be more balanced, but 100 GHz shows better gain and directivity. Multiple band operability makes this antenna suitable for various applications. Finally, a distance-based analysis was conducted to realize the in-depth characteristics of the antenna by placing the antenna at five different gaps from the human body. The result verifies the antenna’s category as suitable for body-centric communications.

Octave-Band Four-Beam Antenna Arrays with Stable Beam Direction Fed by Broadband 4 × 4 Butler Matrix

A novel concept of four-beam antenna arrays operating in a one-octave frequency range that allows stable beam directions and beamwidths to be achieved is proposed. As shown, such radiation patterns can be obtained when radiating elements are appropriately spaced and fed by a broadband 4 × 4 Butler matrix with directional filters connected to its outputs. In this solution, broadband radiating elements are arranged in such a way that, for the lower and upper frequencies, two separate subarrays can be distinguished, each one consisting of identically arranged radiating elements. The subarrays are fed by a broadband Butler matrix at the output to which an appropriate feeding network based on directional filters is connected. These filters ensure smooth signal switching across the operational bandwidth between elements utilized at lower and higher frequency bands. Therefore, as shown, it is possible to control both beamwidths and beam directions of the resulting multi-beam antenna arrays. Moreover, two different concepts of the feeding network connected in between the Butler matrix and radiating elements for lowering the sidelobes are discussed. The theoretical analyses of the proposed antenna arrays are shown and confirmed by measurements of the developed two-antenna arrays consisting of eight and twelve radiating elements, operating in a 2–4 GHz frequency range.