Volume 70, Issue 11-12 -

A compact high isolation MIMO-UWB antenna with triple frequency rejection bands is proposed for UWB communication applications. The proposed MIMO-UWB antenna consists of two identical UWB antennas and each antenna element has a semicircle ring shaped radiation patch fed by a bend microstrip feeding line for covering the UWB band, which operates from 2.85 GHz to 11.79 GHz with an impedance bandwidth of 122.1 %. By etching a L-shaped slot on the ground plane, and embedding an “anchor” shaped stub into the patch and integrating an open ring under the semicircle shaped radiation patch, three notch bands are realized to suppress WiMAX (3.3–3.6 GHz), WLAN(5.725–5.825 GHz) and uplink of X-band satellite (7.9–8.4 GHz) signals. The high isolation with S21<–20 dB in most UWB band is obtained by adding a protruded decoupling structure. The design procedure of the MIMO-UWB antenna is given in detail. The proposed MIMO-UWB antenna is simulated, fabricated and measured. Experimental results demonstrate that the proposed MIMO-UWB antenna has a stable gain, good impedance match, high isolation, low envelope correlation coefficient and good radiation pattern at the UWB operating band and it can provide three designated notch bands.

In this paper, a novel bird face microstrip printed monopole ultra-wideband (UWB) antenna is investigated. The proposed compact antenna consists of a ring-shaped with additional slot and slotted ground plane on FR4 material. The overall electrical dimension of the proposed antenna is 0.25 λ×0.36 λ×0.016 λ and is energized by microstrip feed line. The Computer Simulation Technology (CST) and the High Frequency Structural Simulator (HFSS) is applied in this analysis. The impedance bandwidth of the monopole antenna cover 3.1–12.3 GHz (9.2 GHz, BW) frequency range. The messurement displayed that the designed antenna achieved excellent gain and stable omnidirectional radiation patterns within the UWB. The maximum gain of 6.8 dBi and omnidirectional radiation pattern makes the proposed antenna that is suitable for UWB systems.

A CPW-fed 8-shaped monopole antenna for ultra wideband applications is presented. It consists of a 8-shaped monopole and two quarter elliptical coplanar waveguide ground planes. An impedance bandwidth from 5.4 GHz to 23.83 GHz is achieved. The radiation patterns are observed to be omnidirectional and bidirectional in E-and H-plane respectively at lower resonances. At higher frequencies, the radiation patterns are found to be nearly omnidirectional in both planes. The group delay variation is also observed to be constant in the operating frequency range. A good agreement is found between the simulation and experimental results. The designed antenna structure has miniaturized dimensions and wider bandwidth as compared to other already reported monopole structures.

In this paper, a miniaturized microstrip patch antenna using a negative index metamaterial with modified split-ring resonator (SRR) unit cells is proposed for ultra-wideband (UWB) applications. The new design of metamaterial based microstrip patch antenna has been optimized to provide an improved bandwidth and multiple frequency operations. All the antenna performance parameters are presented in response-graphs. Also it is mentioned that the physical dimensions of the metamaterial based patch antenna are very small, which is convenient to modern communication. A 130 % bandwidth, covering the frequency band of 2.9–13.5 GHz, (for return loss less than or equal –10 dB) is achieved, which allow the antenna to operate in the Federal Communication Commission (FCC) band. In addition, the antenna has a good radiation pattern in the ultra-wide band spectrum, and it is nearly omnidirectional.

In this letter, a compact monopole antenna for ultra wideband (UWB) applications is proposed with small size of 18×20=360 mm 2 . Antenna consist of a flower shape radiating patch with a pair of C-shaped slots which offer two notch bands for WiMAX (3.04–3.68 GHz) & WLAN (4.73–5.76 GHz) and two rectangular shaped slots in the ground plane which provides a wide measured usable fractional extended bandwidth of 163 % (2.83–14.0 GHz) with improved VSWR. Moreover, it is also convenient for other wireless application as close range radar, 8–12 GHz in X-band. Measured radiation patterns exhibits nearly omnidirectional in H-plane and dipole like pattern in E-plane across the bandwidth and furthermore exhibits good time domain performance.

A novel hybrid resonator consists of right handed patch+composite right and left handed transmission line (RH+CRLH) is proposed for the first time aiming at both compactness and frequency manipulation. A demonstration with theoretical dispersion relations and EM simulation is provided for the correctness and efficiency. According to the new method, an ultra-small and dualband antenna operating around 2.4 GHz ( n =0, Bluetooth band) and 3.5 GHz ( n =+1, Wimax band) is designed, fabricated and measured, whose occupied area is only of 0.158λ0×$$\,{{\rm{{\lambda _0}} \times}}$$0.08λ0$$\,{{\lambda _0}}$$. Numerical and experimental results indicate that the antenna exhibits a good impendence match, low cross-polarization and comparable radiation gains in both bands. Excellent performances of the antennas based on hybrid resonators predict promising applications in multifunction wireless communication systems.

This paper reports a simple approach for the design of a compact microstrip antenna at 5.8 GHz. The proposed antenna initially designed with 20 mm × 12 mm radiating element and 65 mm 2 of ground plane in FR4 substrate, provided a –10 dB bandwidth of 300 MHz. Further, parasitic elements are added to improve the antenna bandwidth. A gap-coupled co axial feeding mechanism is also studied for achieving higher impedance bandwidth. It is observed that, antenna with parasitic patches provides a higher impedance bandwidth of 600 MHz with return loss of –30 dB. The prototype of the antenna is fabricated and characterized using a near field measurement system. The results obtained by the experiments are found to agree well with the simulation.

A novel uniplanar CPW-fed tri-band stub-loaded slot antenna is proposed for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. Dual resonant modes were effectively excited in the upper band by using two identical pairs of slot stubs and parasitic slots symmetrically along the arms of a traditional CPW-fed slot dipole, achieving a much wider bandwidth. The middle band was realized by the fundamental mode of the slot dipole. To obtain the lower band, two identical inverted-L-shaped open-ended slots were symmetrically etched in the ground plane. A prototype was fabricated and measured, showing that tri-band operation with 10-dB return loss bandwidths of 150 MHz from 2.375 to 2.525 GHz, 725 MHz from 3.075 to 3.8 GHz, and 1.9 GHz from 5.0 to 6.9 GHz has been achieved. Details of the antenna design as well as the measured and simulated results are presented and discussed.

In this article, a tri-sector cylindrical dielectric resonator antenna (t-CDRA) has been introduced by splitting CDRA into three uniform sectors and all three uniform sectors are packed together in a compact way on a metallic ground plane. A coaxial probe feed is used to excite the proposed composite t-CDRA at the center position. Multi-segmentation approach has been applied for further improvement in bandwidth of proposed t-CDRA. The proposed composite t-CDRA has been designed using HFSS simulation software and analyzed using theoretical analysis. The prototype of t-CDRA, three elements t-CDRA and three elements dual segment t-CDRA has been fabricated for measurement. The input characteristics, near field, far field distribution of the proposed t-CDRAs have been studied through HFSS simulation software and their results are compared with corresponding experimental results. Proposed segmented t-CDRA has wide impedance bandwidth (|S 11 |≤−10 dB) of 85 % with monopole-like radiation pattern. The peak gain of segmented t-CDRA has 5.1 dBi with 98.5 % radiation efficiency. The proposed segmented t-CDRA may find suitable applications in 5.0 GHz WLAN and WiMAX band.

The requirement of unmanned aircraft systems in civil areas is growing. However, provisioning of flight efficiency and safety of unmanned aircraft has critical requirements on wireless communication spectrum resources. Current researches mainly focus on spectrum availability. In this paper, the unmanned aircraft system communication models, including the coverage model and data rate model, and two coexistence analysis procedures, i. e. the interference and noise ratio criterion and frequency-distance-direction criterion, are proposed to analyze spectrum requirements and interference results of the civil unmanned aircraft systems at low altitudes. In addition, explicit explanations are provided. The proposed coexistence analysis criteria are applied to assess unmanned aircraft systems’ uplink and downlink interference performances and to support corresponding spectrum planning. Numerical results demonstrate that the proposed assessments and analysis procedures satisfy requirements of flexible spectrum accessing and safe coexistence among multiple unmanned aircraft systems.

In multiple-input multiple-output (MIMO) systems, spatial demultiplexing at the receiver has its own significance. Thus, several detection techniques have been investigated. There is a tradeoff between computational complexity and optimal performance in most of the detection techniques. One of the detection techniques which gives improved performance and acceptable level of complexity is ordered successive interference cancellation (OSIC) with minimum mean square error (MMSE). However, optimal performance can be achieved by maximum likelihood (ML) detection but at a higher complexity level. Therefore, MMSE-OSIC with candidates (OSIC 2 ) detection is recommended as a solution. In this paper, spatial multiplexed (SM) MIMO systems are considered to evaluate error performance with different detection techniques such as MMSE-OSIC, ML and MMSE-OSIC 2 in a composite fading i. e. Weibull-gamma (WG) fading environment. In WG distribution, Weibull and gamma distribution represent multipath and shadowing effects, respectively. Simulation results illustrate that MMSE-OSIC 2 detection technique gives the improved symbol error rate (SER) performance which is similar to ML performance and its complexity level approaches to MMSE-OSIC.