In this paper, we propose a microstrip filter balun adopting double-sided parallel-strip line (DSPSL) with a conductor plane inserted in the middle of the substrate. Fed by the DSPSL at input port, two microstrip filters on top and bottom layers are excited simultaneously, with the frequency-independent out-of-phase feature obtained between two output ports. The proposed filter balun exhibits excellent performance with good frequency selectivity because of multiple transmission zeros generated by a new coupling scheme. Finally, a filter balun sample is designed and fabricated, and good agreement is obtained between its measured and simulated S-parameters.
A cavity backed conformal broadband compact hexagonal patch antenna is proposed that is fed using a co-axial probe. This horizontally mounted shorted antenna yields vertical polarization. The antenna yields 9.52% bandwidth centered around 1.05 GHz. The simulated results of electrical parameters of this antenna are in good agreement with measured ones. This vertically polarized antenna can be used for IFF airborne applications.
In this paper, a compact microstrip wideband bandpass filter (BPF) based on square ring loaded resonator (SRLR) is proposed. The SRLR is formed by loading a pair of bent open-stubs outside the diagonal corners of a square ring, which generates three split degenerated modes. The first two split modes form a dominant wideband passband. By introducing another pair of loaded open-stubs, the third split mode is moved into the passband to achieve an extra bandwidth for the wideband passband. Measured results show that this proposed BPF has a 3 dB fractional bandwidth of 69%, and the insertion loss of the BPF is less than 1.0 dB.
A design method for four-port crossover with arbitrary phase delay is proposed in this paper. This method is based on admittance matrix. Closed-form design formulations are deduced by making the structure admittance matrix equal to theoretical one. A crossover with 45˚ phase delay is designed and fabricated for theory verification. In the Butler beam forming network, this crossover has two functions for making the elimination of the 45˚ phase shifter possible and being used for circuit layout. Thus compact structure and good performance of Butler network can be realized.
A new wideband and high-gain dielectric resonator antenna (DRA) is proposed. Three cylindrical dielectric resonators (DRs) with different materials and different sizes and a metallic cylinder are designed to obtain a wideband bandwidth and a high gain. The stacked structure provides a wideband bandwidth, and the cavity formed by the metallic cylinder provides a high gain. The measured results demonstrate that the proposed DRA has a wide bandwidth from 5.4 to 7.0 GHz with VSWR less than two and a gain around 11 dBi, covering the frequency range of 26%. The experimental and numerical results are discussed and compared with each other, showing a good agreement between them.
In this paper, we report the possibilities to apply photon sieve principle to binary diffractive lens in millimeter wave band. The FDTD simulation showing the idea of the photon sieve application to millimeter wave optics does not allow increasing resolution power, due to the small number of holes in the FZP aperture. But such simulation results may be used in simple computational experiments in millimeter wave which allows obtaining insight into physical systems characterized by nanometric objects because D/f and D/λ are almost the same.
The development of anatomically and dielectrically representative tissue models is key to the design and refinement of electromagnetic based diagnostic and therapeutic technologies. An important component of any such model are accurate and efficient Debye models which allow for the incorporation of the frequency dependent properties of biological tissues. The establishment of multi-pole Debye models is often a compromise between accuracy and computational cost. Furthermore, some finite difference time domain schemes impose constraints on the minimum Debye pole time-constant. In this study, the authors have developed an optimised genetic algorithm to establish Debye coefficients with minimal yet sufficient Debye poles for several different biological tissues. These Debye coefficients are fitted to existing Cole-Cole models and their accuracy is compared to previously fitted Debye models.
Complementary split ring resonators (CSRRs) are applied on a UWB Vivaldi antenna to eliminate some unwanted narrow band services. Based on the sensitivity of band rejection, we successfully separate the whole radiating patch of a Vivaldi antenna into three subareas: The feeding area, where the Vivaldi antenna demonstrates a highly sensitive response to CSRRs with a narrow notching band; The transition-area, where CSRRs transfer a ultra wideband (UWB) Vivaldi into a narrow band antenna; and the rest area, where CSRRs are proved to have little effects on the antenna bandwidth property. A band notch Vivaldi antenna with 4.8 GHz to 5.4 GHz rejection band is demonstrated to verify our study from both simulated and measured results.
In this article, a novel coplanar waveguide (CPW)-fed miniaturization folded slot antenna for wireless local area network (WLAN) application is proposed and investigated. The multi-operating bands are achieved by folded slot antenna with slot loading. The parametric analysis of the antenna is done by the available electromagnetic solver HFSS11. The designed antenna has a small overall size of 28 mm×30 mm, and operates over the frequency ranges, 90 MHz (2.40 GHz-2.49 GHz), 400 MHz (3.4 GHz-3.8 GHz) and 870 MHz(5.17-6.04 GHz) suitable for WLAN 2.4/5.2/5.8 GHz and WiMAX 3.5/5.5 GHz applications. The proposed antenna is developed, and its measured characteristics are in good agreement with the simulated results. The experimental results show that the antenna gives dipole-like radiation patterns and good antenna gains over the operating bands. In addition, effects of main parameters of the triple-frequency for the design on the electromagnetic performance are examined and discussed in detail.
A high-gain and low-cost circularly polarized antenna array is proposed, which consists of four sequentially rotated circularly polarized square slot antennas (CPSSA). A novel feeding network is applied to the four-element array antenna, which results in increasing the axial ratio (AR) bandwidth. The measured impedance bandwidth for VSWR<2 is around 3.48 GHz (3.75 GHz~7.23 GHz) exhibiting a 2.8 GHz (3.8 GHz~6.6 GHz) 3 dB axial-ratio bandwidth (ARBW) and 9.05 dBic peak gain. The simulated and measured results are in good agreement with each other to verify the design.
In this paper, a novel square-loop quad-mode resonator is presented. Due to its symmetry, the even-odd-mode method is utilized to analyze the resonant characteristics. Two modes resonating at lower frequencies are employed to construct the first passband, and other two form the second passband. Meanwhile, both passband center frequencies can be controlled by the corresponding physical dimensions. Two dual-band bandpass filters (BPFs) without and with source-load coupling operating at 2.4 and 3.5 GHz are designed based on the proposed quad-mode resonator. Due to the source-load coupling, the passband selectivity and band-to-band isolation of the latter one are better than those of the former one. For demonstration, these two filters are fabricated and measured, and the measured results show good agreement with the simulated ones.
A novel structure is proposed as an inline resonator. The resonator has low loss, compact size and good sensing characteristics. A simple analytical form to the plasmonic waveguide discontinuity, filter resonance response and cascaded filters behavior is proposed. The model is extracted from the waveguide physical parameters and provides a physical insight into the structure of the filter. This model is simple, accurate, and shows a good agreement with FDTD simulations. The ability of the model to provide a good methodology to obtain high quality filters using cascaded inline filtering is verified using FDTD. The proposed nanofilter can be used in various plasmonic applications such as sensing, biomedical diagnostics and on-chip interconnects. Using cascaded filters, a higher quality filter is achieved.
We propose a method to obtain nano-scale 3D super-resolution in STED fluorescence microscopy. A double-ring-shaped cylindrical vector vortex beam, with an appropriate vortex angle and a proper truncation parameter of the beam, is used to generate a 3D dark spot as the erase spot. A single-ring-shaped radially polarized beam is used as a pump beam, which can generate a sharper 3D bright spot. The volume of the generated 3D dark spot is small and the uniformity of the light wall surrounding the spot is quite high. Consequently, the 3D super-resolution ability of a STED microscope is improved and nano-scale three-dimensional resolutions are obtained.
A compact coupled-line hairpin resonator is proposed and analyzed for designing a novel bandpass filter (BPF) in this letter. Compared with conventional stepped-impedance and stub-loaded resonator, the proposed resonator can produce three transmission zeros, which can be applied to achieve a wide and highly-attenuated upper stopband. To validate this attractive feature, a microstrip BPF is designed and fabricated with the center frequency at 2.4 GHz and a fractional bandwidth of 6%. Measured frequencies responses show a wider upper stopband up to 6.9 GHz (2.9f0) with insertion loss higher than 20 dB.
This paper presents a new design of high-gain low-profile resonant cavity antenna. A novel partially reflecting surface (PRS) is adopted as the superstrate with the characteristics of high-reflection magnitude and low-reflection phase that allows the reduction of cavity height to about λ/8 and the enhancement of the gain by 10.73 dB. Several significant parameters that characterize the PRS superstrate are investigated based on the unit cell simulation. The measured results show that this method is effective, and this structure can provide a high-gain at the operating frequency. The measured results agree reasonably well with the simulated ones.
This paper presents a novel design of miniaturized microstrip quadrature coupler at 2.45 GHz. The design topology is based on reduced transmission line branch arms using recursively loaded stubs that contribute to the compact size. The proposed coupler result in a size reduction of 70.4% when compared to a conventional branch line hybrid. The designed coupler provides, at the operating frequency, a 25 dB isolation and exhibits equal power division at the output ports with quadrature phase difference. A fabricated prototype is developed with simulation and measurement in close agreement.
The number of OTA antennas of the multi-probe over-the-air (OTA) test system should be large enough for accurate OTA testing yet not too large due to the increasing cost. In this work, the required number of OTA antennas is studied using the spatial correlation function. Some key issues are discussed.
In this paper, we present a wideband monopole antenna loaded with Composite Right Left Hand (CRLH) unit cell for mobile applications. By loading one CRLH unit cell, the monopole antenna can achieve wideband and generate an additional resonant mode much lower than the unloaded antenna's normal frequency. The antenna has a compact size of 0.1λ0×0.15λ0 at the lowest resonance frequency. Measured impedance bandwidth is 2000 MHz (1710~3810 MHz), which can cover one more frequency band for WiMAX applications than conventional antenna. Furthermore, it introduces a narrow band for LTE 700 applications. Stable omni-directional radiation patterns make it suitable for mobile terminals.
A compact printed ultra-wideband (UWB) antenna with band-notched characteristic is proposed. The presented antenna consists of a modified ground plane structure and a novel C-shaped radiation patch fed by a microstrip line. By etching a C-shaped slot in the radiating patch, the notched band of 3.3-3.8 GHz for WiMAX is generated. The notched band can be easily tuned by controlling the size of the slot. The measured results show that the proposed antenna operates over a wide bandwidth from 3 GHz to 16 GHz with return loss less than -10, except a stop-band of 3.3-3.8 GHz. Some key parameters of the antenna are discussed in details. The time-domain characteristics are given.
An on-line method to detect radial mechanical deformations of power transformer winding turns is presented. First-order perturbation theory is applied to a transformer winding surrounded by the transformer tank wall and the iron core. The transformer winding is modeled as thin conducting cylindrical rings (winding segments or turns) situated within a coaxial waveguide, where the outer conducting cylinder represents the transformer tank wall while the inner conducting cylinder represents the iron core. Antennas which radiate and measure microwave fields are proposed inside the transformer tank in order to identify and quantify the mechanical deformations of winding turns. The direct propagation problem is solved using conventional waveguide theory with mode-matching and cascading techniques. An optimization algorithm is then used to solve the inverse problem whereby a good agreement between the reconstructed and true deformations of the winding segments is obtained.
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