Introduction to Electromagnetic Compatibility

In this letter, a novel low-profile microstrip-fed compact triple band-notched ultrawideband (UWB) antenna is proposed. Notch bands around the 3.3-3.8-GHz WiMAX and 5.15-5.85-GHz WLAN frequencies are obtained by etching out two elliptic single complementary split-ring resonators (ESCSRRs) of different dimensions from the radiating patch of the antenna. Furthermore, by placing two rectangular split-ring resonators near the feedline-patch junction of the antenna, rejection for the 7.9-8.4-GHz X-band frequencies is achieved. Design guidelines for implementing the notch-bands at the desired frequency regions are provided. The match between the simulated and experimental results suggests that the proposed antenna can be a good candidate for application in UWB communication systems.

A Compact Microstrip-Fed Triple Band-Notched UWB Monopole Antenna

A monopolar patch antenna with a V-shaped slot for car-to-car (C2C) and wireless local area network (WLAN) communications is presented in this paper. To widen the impedance bandwidth of the antenna, techniques for adding a shorting pin and a V-shaped slot are applied to an equilateral triangular patch. By properly placing the shorting pins on an equilateral triangular patch, two operating modes, i.e., TM10 and TM20, are obtained. The presence of the V-shaped slot can generate an additional TM11 mode. These three resonances found in the operating frequency bandwidth resulted in a wideband characteristic. The proposed antenna can operate from 4.82 to 6.67 GHz for the reflection coefficient $\le -$ 10 dB with the gain of around 5.0 dBi. In addition, an omnidirectional radiation pattern is yielded by a coaxial center-fed probe excitation. The antenna has a thickness of 0.09 $\boldsymbol{\lambda}_\mathbf{g}$ (at the center frequency of 5.5 GHz), which is easily hidden on the roof of a vehicle for C2C communication. This proposed design can also be used as indoor base-station antennas for WLAN communication.

Bandwidth Enhancement of a Monopolar Patch Antenna With V-Shaped Slot for Car-to-Car and WLAN Communications

Because of the inherent structural flexibility in coupling design and topological arrangement, substrate integrated waveguide (SIW) filter topologies enjoy better out-of-band frequency selectivity and/or in-band phase response with the allocation of finite transmission zeros (FTZs). In the first article in this series, basic design rules and fundamental electrical characteristics have been presented that indicate the superior performances of SIW structures and their filter applications. Advanced design techniques and innovative structure features have recently been reported in a large number of publications. They include cross couplings realized by physical and nonphysical paths and SIW filters with dual-mode or multimode techniques. Miniaturization-enabled techniques including low-temperature cofired ceramic (LTCC) technology have been developed and applied to the development of SIW filters to reduce the size for low-gigahertz applications using nontransverse electromagnetic (non-TEM) modes. Wideband SIW filters, multiband SIW filters, and reconfigurable SIW filters have also been reported by various research groups. This article reviews these advanced and innovative SIW filter technologies, and related examples are presented and discussed.

Substrate Integrated Waveguide Filters: Design Techniques and Structure Innovations

Triple band-rejection MIMO/Diversity UWB antenna characteristics are described in this paper. Proposed antenna discards worldwide interoperability for microwave access WiMAX band from 3.3 to 3.6 GHz, wireless local area network WLAN band from 5 to 6 GHz and X-Band satellite downlink communication band from 7.1 to 7.9 GHz. Mushroom Electromagnetic Band Gap (EBG) structures helps to attain band notches in WiMAX and WLAN bands. Uniplanar plus shaped EBG structure is used for notch in X-band downlink satellite communication band. Decoupling strips and slotted ground plane are employed to develop the isolation among two closely spaced UWB monopoles. The individual monopoles are 90° angularly separated with stepped structure which helps to reduce mutual coupling and also contributes towards impedance matching by increasing current path length. Mutual coupling magnitude of more than 15 dB is found over whole UWB frequency range. The Envelope Correlation Coefficient is less than 0.02 over whole UWB frequency range.The variations in the notched frequency with the variations in mushroom EBG structure parameters are investigated.The antenna has been designed using FR-4 substrate and overall dimensions is (64 × 45 × 1.6) mm3.

Triple band notched mushroom and uniplanar EBG structures based UWB MIMO/Diversity antenna with enhanced wide band isolation

The design of a simple multilayered triple band-notched ultrawideband (UWB) antenna is presented in this letter. The proposed antenna is compact in size, suitable for ultrawideband applications, and exhibits triple narrow frequency band notches to suppress the interference of the nearby wireless communication systems within a UWB frequency range. The narrow band notches are realized by adding closed-loop ring resonators designed to cover the 3.3-3.7-GHz, 5.15-5.35-GHz, and 5.725-5.825-GHz bands. The center frequencies of the band notches can be adjusted by varying the ring resonators' mean diameters. The designed antenna has a compact volume of 33 × 30 × 1.524 mm3. The antenna is fabricated and tested providing broadband impedance matching, appropriate gain, and stable radiation pattern.

Ultrawideband Antenna With Triple Band-Notched Characteristics Using Closed-Loop Ring Resonators

A simple design of multilayered quad band-notched ultra-wideband (UWB) antenna is presented. The antenna is compact in size, suitable for UWB applications, and exhibits quad narrow band frequency notches to suppress the interference of the nearby wireless communication systems within a UWB frequency range. The narrow band notches are realised by adding closed-loop ring resonators designed to cover the 3.3–3.7 GHz, 4.5–4.8 GHz, 5.15–5.35 GHz, and 5.725–5.825 GHz bands. The antenna has been fabricated and tested for demonstrating the desired characteristics.

Quad band-notched UWB antenna compatible with WiMAX/INSAT/lower-upper WLAN applications

This paper demonstrates a large-area, lightweight, conformal plasma device that interacts with propagating X-band microwave energy. The active elements are rugged plasma-shells - hollow ceramic shells encapsulating a controlled-pressure gas that can be ionized to controlled plasma parameters. Plasma-shells are electrically excited by frequency selective surfaces that are transparent to the frequency band of interest. The result is equivalent to large-area free-space plasma confined in a discrete plasma slab. A novel structure is designed with the aid of full-wave simulation and fabricated as a 76.2-mm square array, and transmission performance is tested across different drive voltages and angles of incidence. Switchable attenuation of 7 dB is measured across the passband when driven with 1400 Vpp at 1 MHz. Plasma parameters are estimated from theory and full-wave simulation, with electron density estimated to be 3.6×1012 cm-3. The proposed structure has potential for use on mobile platforms.

Development of Large-Area Switchable Plasma Device for X-Band Applications

A novel narrowband filter with integral high-power microwave limiter behavior is proposed to protect cost-sensitive microwave systems The filter-limiter consists of a third-order microstrip bent hairpin filter with encapsulated gas plasma limiters, designed for operation at 870 MHz An equivalent circuit model is presented for the ac-coupled plasma-shell components used in this study, and parameter values were extracted from measured results and electromagnetic simulation The theory of operation of the proposed filter-limiter was experimentally validated and key predictions were demonstrated including two modes of operation in the on-state: a constant output power mode and constant attenuation mode at relatively higher power The filter-limiter operates passively from incident microwave energy, and can also use an external priming voltage source to reduce the limiter turn-on power threshold and reduce output power variation during limiting

Theory and Demonstration of Narrowband Bent Hairpin Filters Integrated With AC-Coupled Plasma Limiter Elements

We propose an ultra-wideband (UWB) antipodal Vivaldi antenna (AVA) with high-Q stopband characteristics based on compact electromagnetic bandgap (EBG) structures. First, an AVA is designed and optimized to operate over an UWB spectrum. Then, two pairs of EBG cells are introduced along the antenna feed line to suppress the frequency components at 3.6–3.9 and 5.6–5.8 GHz (i.e., WiMAX and ISM bands, resp.). Simulated and measured results show a voltage standing wave ratio (VSWR) below 2 for the entire 3.1–10.6 GHz band with high attenuation at the two selected subbands. This simple yet effective approach eliminates the need to deform the antenna radiators with slots/parasitic elements or comprise multilayer substrates. Furthermore, the flexibility it offers in terms of controlling both the number and locations of the band-reject frequencies is advantageous for antennas with nonuniform flares as in the AVA.

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Mohammad Almalkawi

Papers

Ultrawideband Antenna With Triple Band-Notched Characteristics Using Closed-Loop Ring Resonators

Quad band-notched UWB antenna compatible with WiMAX/INSAT/lower-upper WLAN applications

Development of Large-Area Switchable Plasma Device for X-Band Applications

Theory and Demonstration of Narrowband Bent Hairpin Filters Integrated With AC-Coupled Plasma Limiter Elements

Dual Band-Notched Microstrip-Fed Vivaldi Antenna Utilizing Compact EBG Structures