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A folded monopole antenna (FMA) with two different input impedances were investigated to develop an antenna that is robust to metal for applications in a space enclosed by metal objects. An antenna with a variable input impedance is required for improving its robustness to the metal. An FMA with a novel structure is proposed to control the input impedance using a simple configuration. The structure comprises six additional elements parallel to the FMA. However, the number is not limited to six. Some additional elements are electrically connected or disconnected depending on the requirement. Method of moment (MoM) and characteristics mode analysis (CMA) are used in the simulation. The MoM results demonstrate that the input impedance can be adjusted in a step‐wise manner based on the number of additional elements connected to the FMA. This result is similar to that of the input impedance of an FMA with different strip widths considering impedance step‐up ratios (SURs). Furthermore, the change in the antenna characteristics owing to the non‐connected additional elements is minimal. The CMA results reveal that the proposed antenna has the same operation mode as the FMA with different strip widths considering impedance SURs. [ABSTRACT FROM AUTHOR]

A circularly polarized (CP) Microstrip Yagi array antenna (MSYA) is designed in order to achieve high front-to-back ratio R(F/B) and high gain over wide range in the forward radiation space. A Wilkinson power divider owning two output ways with the same magnitude and different phase is used to feed the antenna. Parametric studies are carried out to investigate the effects of some key geometrical sizes on the antenna’s performance. A prototype of the antenna is fabricated, and good agreement between the measured results and the numerical simulations is observed. The overlap bandwidth of VSWR ≤ 1.5 and AR ≤ 3 dB is about 11%. The steering angle (α) between the peak gain direction and the broadside can achieve 35°, R(F/B) reaches 19 dB, and the gain at the front point (G0) is only 4.3 dB lower than the maximum gain (Gm). The antenna has a wide beamwidth CP radiation pattern over wide spatial range including 0° ≤ θ ≤ 90° in vertical plane and −35° ≤ φ ≤ 55° in horizontal plane. [ABSTRACT FROM AUTHOR]

A novel compact chipless RFID tag using spurline resonators is discussed in this paper. The detection of the tag's ID is using the spectral signature of a spurline resonator circuit. The tag has a data capacity of 8-bits in the range 2.38 to 4.04 GHz. The tag consists of a spurline multiresonating circuit and two cross polarized antennas. The prototype of the tag is fabricated on a substrate C-MET/LK4.3 of dielectric constant 4.3 and loss tangent 0.0018. The measured results show that group delay response can also be used to decode the tag's identity. [ABSTRACT FROM AUTHOR]

This study presents a multi-level optimization (MLO) method applied in particle swarm optimization (PSO) to solve a 3-objective optimization problem for an antenna array design consisting of two L-shaped folded monopole antennas (LFMAs) operating in the IEEE 802.11 b/g WLAN band (2400–2484 MHz). The method incorporates a simple concept whereby three sub-objective functions, representing the reflection coefficient S 11, the mutual coupling S 21, and the entire antenna volume of the LFMA array, are minimized one by one in the PSO to obtain an optimal LFMA array configuration that provides reduced size and higher antenna performance. The advantages of the proposed method, both in terms of deriving appropriate optimization results and reducing computational cost for the optimization problem, are demonstrated by comparing its performance with that of a conventional weighted aggregation (CWA) method, and a method using the concept of Pareto dominance (PD). The optimal LFMA array configuration obtained by the proposed method has a 10% resonant bandwidth (S 11 \le -10 dB for 2.32–2.57 GHz), S 21 reduced to less than -15 dB in this band, and an antenna volume that was markedly decreased, to 28.5% of that of the original design. [ABSTRACT FROM AUTHOR]

In this paper, a compact ultra wideband (UWB) monopole antenna with a band-notched characteristic is presented. The band-notched characteristic is achieved by inserting a U-shaped slot in the half elliptical ring radiating patch. The measured bandwidth of the designed antenna for |S11| ≤ -10 dB spans 3.1 GHz to 9.3 GHz with a notched band (|S11| > -10 dB) spanning 5.12 GHz to 5.99 GHz. A quasi-omnidirectional radiation pattern in the x-z plane and quasi-symmetrical radiation patterns in the x-y and y-z planes are obtained throughout the operating band. The antenna is suitable for UWB communication applications and also reduces the interference with wireless local area network (WLAN) systems. The parameters which affect the performance of the antenna in terms of its frequency domain characteristics are investigated in this paper. [ABSTRACT FROM AUTHOR]

The theory and implementation of a new family of monopole antennas loaded with composite right/left handed (CRLH) unit cells are presented. The proposed antennas have a number of narrow bands that is twice the number of unit cells and one wide band that is centered around the monopole original frequency. The new operating frequencies are below the original one and they are controlled by the unit cell dispersion relation. The proposed antennas occupy the same Chu sphere as the original monopole, all the operating frequencies have omni-directional radiation patterns, and matching is better than -10 dB. Three antennas are realized; the first is loaded with one distributed CRLH unit cell, the second is loaded with lumped components CRLH unit cell, and the third is loaded with two CRLH unit cells. All proposed antennas are fabricated and measured. Measurements and EM simulations confirm the proposed theory. [ABSTRACT FROM PUBLISHER]

A novel broadband design of planar arc-shaped monopole antenna with a rectangular parasitic patch for UWB system is proposed. With the use of rectangular parasitic patch, multi resonant modes are excited to meet the specifications of UWB system. Moreover, the obtained impedance bandwidth across the operating band can reach about 10.25 GHz. The measured peak gains and radiation efficiencies are about 1.2–5.3 dBi and 85–91% across the operating band, respectively, with nearly omni-directional pattern in the XY-plane. [ABSTRACT FROM PUBLISHER]

In this paper, we propose several array topologies to achieve good power-combining characteristics for the open slot antenna. By utilizing an appropriate feeding structure and injecting in- phase or out-of-phase signals, power-combining radiation patterns can be derived. Simulated surface current distributions of several antenna structures are presented to explain radiation mechanism. From the results of radiation performance, the advantages of gain enhancement and pattern reconfiguration are shown. By varying the phase difference of two injected signals of the open slot antenna array, two-dimensional beam-scanning radiation patterns are successfully demonstrated. [ABSTRACT FROM AUTHOR]

A novel wide-band printed antenna, named forked shape monopole antenna (FSMA), is proposed. The forked shape line structure is introduced to create a capacitive coupling effect to reduce the antenna size and enhance the impedance bandwidth. The proposed antenna is to be applied in a compact USB dongle. And it is designed for the reception of the digital video broadcasting (DVB) signal in the 470 \sim 860 MHz frequency band. In addition to the DVB application, the upper band limit of the FSMA even can be extended from 860 MHz to 1142 MHz, suitable for use in the Global System for Mobil Communication (GSM850/900). By employing the branched-line and forked shape configurations, an antenna with 86% impedance bandwidth (SWR<2.5) is provided. A prototype of the FSMA was constructed and demonstrated. Measured and simulated results for the FSMA alone and with real application on a laptop computer are obtained. [ABSTRACT FROM PUBLISHER]

Novel integrated planar monopole antennas with various microstrip resonators are presented. The proposed integrated antennas consist of wideband planar monopole antennas and electromagnetically coupled microstrip resonators producing band-notched characteristics. Various types of microstrip resonators such as open-circuited line resonator, short-circuited line resonator, closed-loop resonator and open-loop resonator are described. The proposed designs are suitable for wideband antennas with narrowband interferer rejection characteristic or multi-band antennas. [ABSTRACT FROM AUTHOR]

An internal clamshell mobile phone antenna using a simple dual-band folded monopole slot for covering penta bands of WWAN operation is presented. The folded monopole slot has a length of about 60 mm only and is easily printed on the top portion (10 x 40 mm2 ) of the main circuit board and suitable to be placed at the hinge of the clamshell mobile phone. By further placing the connecting strip between the two ground planes to be in the vicinity of the open end of the monopole slot, the two (main and upper) ground planes of the clamshell mobile phone can also be excited to be efficient radiators (dipole-like chassis or groundplane modes excited through the strong electric field occurred at the slot's open end). By incorporating the resonant modes contributed from both the monopole slot and the two ground planes, two wide bands at about 900 and 1900 MHz are formed, which easily cover GSM850/900/1800/1900/UMTS operation. Owing to the additional resonant modes contributed by the two ground planes, the use of a simple folded monopole slot is sufficient to cover penta-bandWWAN operation. This leads to compact size for the proposed clamshell mobile phone antenna. Details of the proposed antenna, including its SAR results, are presented. [ABSTRACT FROM AUTHOR]

This paper presents the analysis, design and measurement of novel, low-profile, small-footprint folded monopoles employing planar metamaterial phase-shifting lines. These lines are composed of fully-printed spiral elements, that are inductively coupled and hence exhibit an effective high-ia property. An equivalent circuit for the proposed structure is presented, validating the operating principles of the antenna and the metamaterial line. The impact of the antenna profile and the ground plane size on the antenna performance is investigated using accurate full-wave simulations. A )t/9 antenna prototype, designed to operate at 2.36 GHz, is fabricated and tested on both electrically large and small ground planes, achieving on average 80% radiation efficiency, 5% (110 MHz) and 2.5% (55 MHz) -10 dB measured bandwidths, respectively, and fully omnidirectional, vertically polarized, monopole-type radiation patterns. [ABSTRACT FROM AUTHOR]

An antenna that is used at both the transmit and receive end of the same dispersionless communications link should have a time domain response that looks like a half-derivative on transmit, at least over the frequency range of interest. Time domain reciprocity then dictates that the antenna will compensate for this half-derivative when used as the receiver, producing a flat channel response in the frequency domain. The desired waveform is produced by a pulsed infinite line source. An antenna concept based on a partially focused transverse electromagnetic horn might be able to mimic this performance over a finite frequency range. [ABSTRACT FROM AUTHOR]

We propose a stochastic model for multiple-input multiple- output (MIMO) communication systems based on the eigendecomposition of the spatial correlation matrix. It is shown that the channel matrix can be well modeled by the superposition of the spatial eigenmodes experiencing independent Nakagami-m fading. The proposed scheme is also compared with the existing correlation-based models using the data obtained from an indoor measurement campaign so that its performance is assessed in depth. [ABSTRACT FROM AUTHOR]

The idea of so-called macromodels is applied to problems of computational electromagnetics involving integral-equation/method-of-moments formulations. It is shown that with the use of equivalence principles, it is possible to exclude a part of the problem, calculate its wideband response without an a priori knowledge of the excitations, and then efficiently combine the result into the original situation. The idea is validated using examples involving slot-excited dielectric resonator antennas. [ABSTRACT FROM AUTHOR]

The performance of radar target identification using the natural E-Pulse technique is significantly degraded if the sampling rates of the target response and the E-Pulse filter are ignored. In this work, improved sampling procedures over that previously reported by Antony and Shuley (Electron. Lett., vol. 40) in 2004 are proposed. Numerical results demonstrate that the proposed procedures significantly improve the target identification performance. [ABSTRACT FROM AUTHOR]

We indicate that the two-dimensional (2-D) direction-of-arrival (DOA) estimation method proposed by N. Tayem et at. has an error in the pair matching between the azimuth and elevation angle estimates. A feasible solution for pair matching is proposed. [ABSTRACT FROM AUTHOR]

A wideband single chip inductor-loaded coplanar waveguide (CPW)-fed inductive slot antenna is proposed and experimentally studied in this paper. In order to have bandwidth broadened and dimensions controlled as well, an inductor with optimal value is shunt at one far end of the inductive slot antenna to help excite an additional lower resonance point. Moreover, the bandwidth is further widened by enlarging the over-the-slot ground height. With both the optimal chip inductor and ground height values, a 10 dB return loss bandwidth of (34.5%, 1756 MHz) centered at 5083 MHz is achieved, which is, in percentage, 3.7 times the (9.3%, 531 MHZ) bandwidth of the 5666 MHz stand-alone CPW-fed inductive slot antenna. [ABSTRACT FROM AUTHOR]

A broadband plate antenna operating at a frequency range of 3-12 GHz is proposed for ultrawideband (UWB) applications. The plate antenna consists of a shorting wall attached to the radiator. The radiator is excited by a parasitic L-shaped plate connected to a feeding probe. The vertical section of the L-shaped feeding plate is separated at a distance from the shorting wall. With the electromagnetic coupling between the feeding plate and the radiator, a broad impedance bandwidth is achieved. Also, the antenna with reduced size is able to achieve the stable radiation performance with gain greater than 4 dBi across the entire UWB band. [ABSTRACT FROM AUTHOR]

The design of a dual-polarization stacked patch antenna to be used in GSM-UMTS base station arrays is presented. The patch shows a high matching level in a broadband and isolation between elements that make it a suitable radiating element for base station arrays. Moreover, the most relevant achievement of this element is the isolation between the two polarization ports of the same element in the antenna operating bandwidth. A prototype has been manufactured and measured. The measurements, that match the design objectives, are also presented. [ABSTRACT FROM AUTHOR]

A comprehensive and integrative overview (excluding ultrawideband measurements) is given of all the empirical data available from the open literature on various temporal properties of the indoor radiowave communication channel. The concerned frequency range spans over 0.8-8 GHz. Originally, these data were presented in about 70 papers in various journals, at diverse conferences, and in different books. Herein overviewed are the multipaths' amplitude versus arrival delay, the probability of multipath arrival versus arrival delay, the multipath amplitude's temporal correlation, the power delay profile and associated time dispersion parameters (e.g., the RMS delay spread and the mean delay), the coherence bandwidth, and empirically "tuned" tapped-delayline models. Supported by the present authors' new analysis, this paper discusses how these channel-fading metrics depend on the indoor radiowave propagation channel's various properties, (e.g., the physical environment, the floor layout, the construction materials, the furnishing's locations and electromagnetic properties) as well as the transmitted signal's carrier-frequency, the transmitting-antenna's location, the receiving-antenna's location, and the receiver's detection amplitude threshold. [ABSTRACT FROM AUTHOR]

A previously published guideline for MIMO antenna arrays is refuted. The influence of radiation efficiency on diversity gain and MIMO capacity of wireless communications systems is investigated through simulations and measurements using a reverberation chamber. Integrated antennas on a portable device have efficiencies low enough to disallow typical inter-element correlation assumptions. Both diversity gain and MIMO capacity depend on the number of antennas, SNR and efficiency in a complex way. When the efficiency of antennas is considered, certain system capacity losses are predicted and measured. These losses may be recovered through using more receive elements than commonly recommended or through the addition of a smaller number of more efficient antennas. [ABSTRACT FROM AUTHOR]

A design is proposed of a multiresonant monopole antenna for a personal wireless communication handset. Multiresonant operation is achieved through the use of a bent tuning stub, a shorting strip line, a U-shaped slit and the addition of a narrow resonant slit to the main radiator. The first resonant frequency is determined by the main radiator of the proposed antenna, and the second resonant frequency is controlled by the length of the bent tuning stub. The third resonant frequency is generated by adding a narrow resonant slit to the perimeter of the main radiator. The three resonant frequencies of the designed antenna can be independently controlled by tuning the length of the individual elements of the proposed antenna. The measurement shows the intended four wireless communication services: Global System for Mobile communication (GSM900), Digital Communication System (DCS1800), US-Personal Communication System (US-PCS), and Satellite-Digital Multimedia Broadcasting (S-DMB). The proposed antenna is small enough to be built into a practical wireless mobile handset. The parameters determining the antenna's multiresonant characteristics are analyzed, and experimental results of the constructed prototype are presented and discussed. [ABSTRACT FROM AUTHOR]

This paper presents the design equations for lower band-edge frequency for all the regular shapes of printed monopole antennas with various feed positions. The length of the feed transmission line is a critical design parameter of these monopole antennas. Design curves for the length of the feed transmission line for various lower band-edge frequencies for all these regular shaped monopoles have been generated. A systematic study has been presented to explain the ultra-wide bandwidth obtained from these antennas with an example of elliptical monopole antenna. [ABSTRACT FROM AUTHOR]

A printed ultra wideband (UWB) monopole antenna is proposed for applications on stepped frequency continuous wave (SFCW) ground penetrating radar (GPR) within a frequency range of 100-1000 MHz. The proposed antenna consists of a hexagonal strip line with resistive loading and a rectangular slot that is added to the ground plane side of the printed antenna implemented on FR4 epoxy materials. The resistive loading at the hexagonal monopole is effective to increase bandwidth in the higher frequency region, while the rectangular slot is used to improve bandwidth characteristic in the lower frequency region. This paper investigates the characteristic improvement in the lower frequency region by applying a parametric study on the rectangular slot that is added at the ground plane side of the UWB monopole antenna. Computer simulation was conducted and measurements were carried out to validate the result. [ABSTRACT FROM AUTHOR]

We propose a new band-notched folded strip monopole antenna for ultrawideband applications. This antenna is composed of a forked-shape radiator and a 50 Ω microstrip line. To achieve band-rejected filtering property at the WLAN bands, the forked-shape strips are folded back and result in a pair of coupled lines on the radiator. The length and gap width of the coupled lines primarily determine the notched frequency of the antenna. Based on the band-notched resonance, an equivalent circuit model is proposed for the antenna and the calculated antenna input admittance agrees with the full-wave simulation data. With the help of the dimensionless normalized antenna transfer function, the radiation characteristics are investigated thoroughly. The transmission responses of a transceiving antenna system and their corresponding transient analysis are discussed at the end of this paper. [ABSTRACT FROM AUTHOR]

An effective frequency domain full-wave approach is proposed for the simulation of time modulated (TM) linear arrays with variable aperture size (VAS) time schemes. The full-wave simulation of the TM linear arrays is fulfilled by combination of the frequency domain full-wave simulation results of the corresponding regular linear arrays at multiples of the modulation frequency. Numerical simulation results of two TM linear arrays with VAS time schemes are presented and are compared with reported measurement results, and close agreement is obtained through comparison. [ABSTRACT FROM AUTHOR]

A single-fed circularly polarized stacked patch antenna is proposed to cover all GPS bands, including the E5a/E5b band for the Galileo system. The small aperture size (λ8 at 1176 MHz, the L5 band) makes this antenna attractive for small GPS arrays. Also, in contrast to previous GPS antennas, the presented design uses a single feed for circular polarization. In this paper, we present the design procedures and performance of the designed GPS antenna and discuss issues relating to coupling between array elements. Modifications to reduce coupling are then presented. [ABSTRACT FROM AUTHOR]

A miniaturised broadband top-loaded planar monopole (TLPM) antenna with binary-encoded sleeves is proposed. The antenna consists of a TLPM with an embedded artificial transmission line to reduce the operating frequency. To broaden the operating bandwidth of the proposed miniaturised monopole antenna, the binary-encoded sleeves are utilised and optimised using a genetic algorithm. A prototype of the proposed antenna is fabricated and tested. The measured -10 dB reflection coefficient bandwidth is 800-1265 MHz (45.04%). A peak gain of 4.11 dBi and consistent radiation patterns are achieved within the operating frequency band. [ABSTRACT FROM AUTHOR]