A new planar bow-tie antenna is proposed here for UWB applications. The self-complementary principle has been applied to a planar triangular monopole antenna along with bending the microstrip feed line. The antenna has a wider frequency band compared to the traditional bow-tie antenna, complies with the UWB requirements and it is directly matched to the (SMA) connector via 50 Ω microstrip feed line. This antenna has a simple shape which overcomes the complicated matching techniques using baluns or impedance matching sections that are commonly used in bow-tie antennas for widening their limited bandwidths. Another improvement on this new bow-tie antenna is achieved through fractal self-similarity repetition of the triangular shape on each of the patch and its complimentary slot. The simulation results obtained from the CST and HFSS software packages are verified by experimental measurements.
A minimized wideband antenna array is presented for ultra-high frequency (UHF) radio frequency identification (RFID) reader applications. The antenna array consists of two E-shaped patch antennas and a feeding network, with the overall size 200×100×20 mm3. The feeding network could effectively decrease the antenna mutual coupling and improve the bandwidth. The measured bandwidth is about 68 MHz (896-964 MHz) under the condition of voltage standing wave ratio (VSWR) less than 2, which covers various RFID bands including North American (902-928 MHz), partial Chinese (920-925 MHz) and Japanese (952-955 MHz). The average gain is 4.5 dBi in UHF band. The principles of the antenna and the feeding network are also discussed and analyzed in this paper. At last, the key parameters are studied and show the antenna robustness.
A new compensation method for the mutual coupling of adaptive antenna arrays composed of wire elements is introduced. For the antenna array composed of wire elements, the new compensation method can decouple the terminal voltages with high accuracy for both the 1-D incident signals and 2-D incident signals. The new compensation method is based on the mutual coupling grid and the transient mutual coupling coefficient proposed in this paper. By contrast with the CMIM and RMIM, the new compensation method can provide better compensation for the DOA estimations. Even for the ultra compact antenna array and the incident signals inclined with respect to the azimuth the new compensation method can work well. The numerical results verify the validity and the effectiveness of the new compensation method.
A novel compact ultrawideband (UWB) CPW-fed antenna with triple lower pass bands and dual notched bands for wireless applications is presented. The low-profile antenna comprises of an approximate hexagonal-shaped radiator for covering the UWB band (3.1~10.8 GHz). Triple lower pass bands, the 1.5G band, 1.8 GHz GSM band and 2.4 GHz Bluetooth band, can be realized by adding three handstand semielliptical-shaped stubs bilaterally at the upper part of antenna ground. A notched band of 3.3~3.7 GHz for rejection of WIMAX radio signals can also be obtained by adjusting the geometry of the three stubs. In addition, an U-shaped slot on the radiating patch generates a notched band in 5.15~5.825 GHz for rejection of WLAN radio signals. The proposed antenna is designed and built on a FR-4 substrate, with overall size of 25 mm×24 mm. The simulated and measured results are presented and show that the proposed compact antenna has a stable and omnidirectional radiation patterns across all the relevant bands.
This paper presents a novel design of stacked dual layer strip lines fed patch antenna. The wideband characteristics can be achieved by employing approximate L-probes coupling feeding schemes. Dual layer strip lines which are composed of one broadband 180° hybrid and two wideband 90° hybrids are introduced as feeding network in this design. As a result, the designed antenna has a 59.4% 10-dB input reflection coefficient bandwidth and 48.3% 3-dB axial ratio (AR) bandwidth relative to the center frequency respectively. The designed antenna occupies a compact size of 80 mm×80 mm×32 mm. The final antenna provides a very good circularly polarized radiation for Global Navigation Satellite System applications including GPS, GLONASS, Galileo and Compass.
In this paper, a novel interactive multiple model particle filter (IMMPF) is developed after a Bayesian estimator for maneuvering target tracking in clutter is derived theoretically. In this new algorithm, base state estimation and modal state estimation are completely separated to control the number of particles in each maneuvering mode. Only continuous-valued particles are used to numerically implement the procedure of Bayesian base state estimation, whereas modal state is estimated analytically without dependence on the number of particles. Density mixing is performed by aggregation of the total particles and mixing associated weights. To prevent the exponentially growing number of particles with the time, a resampling step is included following the interaction step. Through MC simulations, the new IMMPF has been tested and shown to provide reliable performance improvements with different sample sizes and under various clutter conditions.
In this paper, a printed slot antenna fed by a co-planar waveguide for ultra wide bandwidth (UWB) with dual notch bands has been presented and discussed. The band notches are realized by etching one C-slot resonator inside a plaque shape exciting stub as well as symmetrically adding a pair of open-circuit stubs at the edge of the slot resulting in dual stop band filtering properties for WiMAX, WLAN application. Surface current distributions are used to analyze the effects of the slot and open circuit stub. The proposed antenna is fabricated and experimental results show that it has an impedance bandwidth of 2.6-14.34 GHz for VSWR ≤ 2, except dual frequency stop-bands of 3.3-3.7, 5.04-6.0 GHz. From the simulation results, it is observed that the radiation patterns are omnidirectional in the H-plane and dipole like nature in the E-plane. The gain varies from 3.7 dB to 5.7 dB over the whole UWB region excluding at notch bands.
In this paper, broadband transitions from substrate integrated coaxial line (SICL) to a conductor-backed coplanar waveguide (CBCPW) are proposed and designed. Measurement results show that the insertion loss and return loss are better than -0.5 dB and -10 dB, respectively from 0 to 13 GHz. Then, for verifying the performance of SICL and the validity of SICL transition design, a 3 dB SICL rat-race coupler operating at 2.3 GHz is designed, fabricated, and measured. Compared with the conventional microstrip line coupler, this SICL coupler maintains good performance but with a remarkable 24% reduction in size. At last, a 10 dB dual-band coupled SICL coupler operating at 2.4/5.8 GHz is proposed, and the measured results agree well with the schematic and electromagnetic simulated results. The measured results demonstrate that the fabricated bandwidths are 30% and 12.8%, the |S31| are -10.1 dB and -10.3 dB, the directivities are 18 dB and 20 dB at the low (2.4 GHz) and high (5.8 GHz) operating frequencies, respectively. Compare with the dual-band coupled microstrip line coupler, performance of the dual-band coupled SICL coupler is enhanced.
Novel reconfigurable frequency selective surfaces (RFSS) are designed using a finite-difference time-domain with periodic boundary condition (FDTD/PBC) algorithm. The FSS are reconfigured using two techniques: the first technique providing a wide frequency tuning range is based on using diodes to change the current distribution over the FSS surface, and the second technique exhibiting a finer frequency tuning resolution is based on changing the grid orientation of the FSS mechanically. Simulation results are provided to validate the concept of RFSS. The results show that these designs provide a wide dynamic range of reconfigurability and a large degree of freedom in controlling the FSS frequency response.
A compact circularly polarized shorted annular stacked patch antenna has been proposed for global navigation satellite system (GNSS) in this paper. The antenna has been designed to operate for the satellite navigation frequencies including GPS, GLONASS, Galileo and Compass (1100MHz-1600 MHz). In order to obtain wideband characteristics, broadband 90° hybrids have been used as a secondary network. The designed antenna has a 73.7% 10-dB return loss bandwidth from 0.9 GHz to 1.95GHz, and 60.1% 3-dB axial ratio bandwidth from 0.96 GHz to 1.8 GHz, respectively. Shorted annular stacked patch structure is incorporated into the antenna design helping to obtain stable gain bandwidth, broad beamwidth characteristics and good axial ratio at low elevation. The designed antenna occupies a compact size of 100 mm×100 mm×15.5 mm.
This paper shows the design of a reduced size system that drives local oscillator (LO) signal generated by a voltage controlled oscillator (VCO) in the transceiver system, which is based on I and Q architecture. The aim of this work is to obtain a small system capable to drive two differential mixers and one phase locked loop block with high power efficiency. The entire system drives two differential outputs to their respective mixers with a minimum differential LO power of -1 dBm and a maximum of 0 dBm between 56.5 and 60 GHz. The system furnishes -7dBm to the PLL, allowing the control of the carrier. The output ports are matched at 50 Ω and they achieve a reflection loss under 10 dB in the whole band of interest. The power consumption of the entire system is 58 mW. The size including RF and DC pads is 0.6×0.7 mm2.
Equivalent charge method is used to design ultra wide band asymptotic conical dipole (ACD) antenna. Combination of linear charge density and point charges is used to generate different profiles for ACD antennas. Two different profiles of ACD antenna are used as a feed for reflector based impulse-radiating antennas (IRAs). This paper focuses on the selection of ideal ACD profile as well as the requisite charge distribution for ACD antenna as a feed to design 100 Ω input impedance reflector IRA. An ideal Configuration of ACD feeding structure for reflector IRA is chosen based on FDTD analysis results. To validate the utility of the proposed new feed an ACD-fed half IRA is realized with input impedance of nearly 50 Ω. Measurements are carried out using single-ended instrumentation without any impedance adaptor as commonly done with Conventional IRAs.
The effect of human body on inkjet-printed flexible single-layer transmission lines in immediate proximity of body is investigated by simulations and measurements up to 9 GHz. A multliine extraction method is used to obtain effective material parameters allowing detailed analysis of body effects. Already at 1 mm distance from the body, the line properties converge toward the free-space values. However, at smaller distances and in direct contact with the body, often required in biosensor applications, there is a significant change in characteristic impedance and increase in losses. The results of the paper can be used to evaluate the body effects at different frequencies and at different small distances from the body.
Magnetic resonance imaging (MRI) is a well established non-invasive technique to retrieve structural information from plants and fruits. Water transport inside these materials has also been studied with MRI, however, the integrate combination of studying both structure and dynamics has hardly been considered. Here it is shown how the anisotropic nature of water diffusion in channels or vessels inside the plant, combined with plant structural information, can be used to map these vessels in three dimensions. Diffusion Tensor Imaging (DTI), an MR technique initially introduced to study white matter in mammalian brains, is used to track water transport pathways inside Thompson Seedless grapes and celery as an example.
A compact dual-band antenna for WLAN applications and Long Term Evolution (LTE) services in the 800 MHz band is designed. The compactness, the robustness, and the simplicity of the proposed solution make it suitable for the integration in recent and widely diffused mobile and multi-standard devices. The multiband behavior is yielded by exploiting a Sierpinski Gasket fractal shape whose descriptors are perturbed by means of a particle swarm optimization (PSO) strategy to fit the performance requirements. The results assess the good matching between numerical simulations and experimental validations as well as the effectiveness of the prototype in reaching a suitable impedance matching and satisfactory radiation characteristics.
A dual-band bandpass filter with wide and highly attenuated stopbands is designed using parallel coupled microstrip line (PCML) and stepped-impedance-resonators (SIRs). The proposed filter is composed of a pair of highly coupled PCML-SIR structure and a central resonator using a low impedance rectangular microstrip. Initially, the wide dual-band performance is achieved by creating a transmission zero between those two bands using a tightly coupled PCML-SIR with a suitable impedance ratio. Then, a low impedance resonator is placed between the pair of PCML-SIR to generate multiple resonant frequencies for a broadband performance. The simulated and measured results of those filters agree very well. The bandwidth of the first band in the developed filters extends from 1.75 GHz to 3.75 GHz with less than 0.3 dB insertion loss at the center of the band. The second band has a bandwidth that extends from 6.95 GHz to 8.75 GHz with less than 0.5 dB insertion loss at the center of that band. The stopband separating those two passband has more than 30 dB attenuation with transmission zero at 5.85 GHz.
Space-Time Adaptive Processing (STAP) algorithm has recently been used in Passive Bi-static Radars (PBR) because it removes the clutter and non-cooperative transmitter effectively making the target detection easy in harsh environments like air-ground. Real-time implementation of STAP is a very challenging task as it is computationally-intensive, time-critical and resource-hungry process. This paper focuses on the Field-Programmable Gate Array (FPGA) implementation of STAP algorithm for passive radar using FM radio as transmitter of opportunity. The signals of interest were collected using an eight-channel software-defined radar with a uniform circular array (UCA). The STAP processing was simulated using MATLAB and hardware implementation was carried out on a Xilinx Virtex-6 FPGA. The system is tested using experimental radar data. Timing and Power analysis of hardware implementation justifies that FPGA provides a fast and reliable platform for STAP real-time radar processing.
In this paper, a compact ultra wideband (UWB) monopole antenna with a band-notched characteristic is presented. The bandnotched 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 quasisymmetrical 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.
A class E power amplifier including coupling coils is proposed for application in a wireless power transfer system using magnetic coupling. The proposed amplifier is directly connected to the coils with no discrete components for harmonic filtering and dc feeding, which could cause efficiency degradation of the amplifier. The system with the differential amplifier shows 6.95 W of transmitted power and 44.6% transmission efficiency at 6.8 MHz with 14-cm distant coils. The power-added efficiency of the amplifier is 92.1% with a 14 V supply voltage, excluding the coupling efficiency of the wireless power transfer network.
In this paper, we will present a quasi-elliptic bandstop filter using asynchronously tuned resonators. To demonstrate this technique, a novel broadband microstrip bandstop filter is also proposed using distributed resonators. To achieve wide bandwidth using distributed resonators, strong couplings are required. This is achieved using tap coupled to avoid very narrow gaps which are costly to manufacture. The filter exhibits a factional bandwidth of approximately 35%. A simple practical transformation technique for transforming Chebyshev bandstop filter to asynchronously tuned quasi-elliptic bandstop filter will be presented.