In this paper, an on-chip high integration reconfigurable dipole with band stop filters was demonstrated. This antenna was fabricated on a high resistivity silicon wafer, and several optimized band stop filters were introduced into antenna system to replace conventional inductors and capacitors. The measured results show that the stopband of this filter can meet the requirements of the designed dipole. This method will greatly improve the integration of antenna system. On the basis of structural optimization, the proposed reconfigurable dipole realized two resonant frequencies at 1.33 GHz and 1.65 GHz, and the radiation patterns also showed satisfactory results.
This letter presents the development of a miniaturized and folded multisection quadrature hybrid for ultra-wideband (UWB) applications. For a size reduction, Stages 1, 2 and 3 are placed on the top of PCB, and Stages 5, 7 and 7 are placed on the bottom of PCB. The transition between top and bottom layers uses via transitions. Stage 4 is proposed with vertical via transitions and microstrip lines on the top and bottom sides of PCB, which is helpful for bandwidth increment and size reduction. The overall size of the proposed UWB hybrid is only 21 mm by 14 mm, and a size reduction of 50% is achieved compared with a planar multisection one. Performance comparisons are also implemented and discussed compared with a planar one.
In this paper, a novel HMSIW slot antenna combines a significant bandwidth enhancement and small footprint for inter-satellite communications at C-band. The designed antenna has the capability of achieving a reduction of size with nearly 50% in comparison to conventional SIWs. The results show that the proposed antenna has a bandwidth of 4%, an average gain of 5.8 dB, and the radiation efficiency of η = 93% at 5 GHz.
A polarization matched 2×2 radiating array for electronically steered phased array antenna is presented. The antenna array is a multi-layer structure consisting of four square microstrip patch elements grown on each substrate to provide wide band operation at S-band. Dual polarizations of radiated wave from the antenna array have been achieved by feeding the array in series fed mode through horizontal and vertical ports. Designed 2×2 S-band dual polarized series fed antenna has been optimized on finite element based ANSYS HFSS full wave solver. Controlling the amplitude of RF signal at input ports, the polarization can be matched to the target antenna polarization, hence antenna can work as polarization matched antenna. Gain of the developed antenna is 13 dBi, and the return loss is better than 10 dB over the frequency range of 2.3 to 2.5 GHz. This antenna can be used as radiating array for electronically steered phased array for S-band SOTM (SATCOM On The Move) application where the polarization of the antenna changes with movement of host platform.
A concept of an experimental simulator for studying longitudinal magnetic waves in dielectric samples and its electrodynamic justification are presented. The simulator is intended to control impact power and frequencies of wave processes. The simulator is realized as a two-channel junction consisting of perpendicularly crossed infinite rectangular waveguides with slot coupling. The simulation process is based on cyclic mechanical displacements of dielectric samples along the longitudinal axis of the waveguide in a quasistationary magnetic field localized in the slot region.
We report on the experimental verification of the employment of equivalent parameters in a 2D finite element model to describe absorptivity of curve-shaped, large-scale metamaterial structures. Equivalent homogeneous optical parameters were retrieved from experimental measurements of flat metamaterial sheets with square resonators of 8 and 9 mm and used in a 2D FE model to obtain the absorptivity of curved structures with similar metamaterial unit cells. The curved structures were experimentally characterized and showed good agreement with the model. The tremendous simplification made possible by simulating complex structures as homogeneous materials makes the method very attractive for designing large-scale electromagnetic shields and absorbers.
An airborne phased-multiple-input-multiple-output (Phased-MIMO) radar with collocated antenna array is a tradeoff of phased array radar and MIMO radar. Its transmitting array is divided into multiple subarrays that are allowed to be overlapped. In this letter, we mainly study the array partitioning scheme of the airborne Phased-MIMO radar with equal uniform linear subarrays that are fully overlapped on the basis of space-time adaptive processing (STAP). A mathematical formula is derived to determine the number of subarrays and the elements in each subarray according to the principle of maximum STAP signal-to-interference-plus-noise ratio (SINR). The SINR performances corresponding to different partitioning schemes are simulated and discussed to demonstrate the effectiveness of the proposed mathematical formula for array partitioning in the sense of maximum STAP SINR.
A dual-band flexible antenna incorporated with the fractal structure using coplanar waveguide (CPW) is proposed for 2.42 GHz WLAN and 3.78 GHz WiMAX applications. The antenna is printed on a low-cost FR4 substrate having a thickness of 0.5 mm with overall antenna dimension of 97.48x80 mm2. Incorporation of fractal geometry leads to improvement in terms of impedance bandwidth and radiation efficiency. The simulated and measured results of the proposed antenna in terms of return loss (S11), gain, radiation pattern, and VSWR are presented here which show great correlation. The measured impedance bandwidth and gain of the flexible antenna are 17.08% (2.20 GHz-2.61 GHz), 16.30% (3.38 GHz-3.98 GHz), 4.56 dBi and 1.09 dBi, respectively. The proposed dual-band antenna shows omnidirectional and bidirectional radiation patterns in H and E-planes which makes it suitable for its use in low-cost Bluetooth/WLAN/WPAN/WiMAX applications.
Conical and cylindrical dielectric resonator elements are vertically stacked and excited by a simple coaxial monopole. Compared to all earlier configurations, the proposed geometry significantly improves the impedance bandwidth. The ultrawideband response is enhanced due to the multiple resonances occurring by the suggested hybrid antenna. The footprint area of the antenna is only 63.6 mm2 or 25.44 x10-3λo 2 at the lowest operating frequency. The performance of the antenna is verified experimentally and numerically. Presented results show that the proposed hybrid monopole-DRA has a measured impedance bandwidth up to 148.6% (S11 < -10 dB) along with consistent monopole-like radiation patterns and peak gain of 7.14 dBi. With such properties, the proposed hybrid monopole-DRA can be used in different ultra-wideband wireless applications and as wideband electromagnetic interference (EMI) sensors.
This work describes the fabrication and characterization of a frequency reconfigurable patch antenna using ferrofluid actuation. The reconfiguration is based on a variation of dielectric constant of the substrate. For this, the substrate is modified by placing channels in it filled with ferrofluid and isopropanol-water solution. The relative position of ferrofluid along the channels is controlled by an external magnetic field which results in a relocatable spatial difference in the dielectric constant value. The targeted reconfigurability with stable radiation characteristics at the accessible frequencies is validated through antenna reflection loss and radiation pattern measurements. Additionally, actuation speed of the fluid immerged in the polar mixture is measured by sequential image analysis.
This letter presents a novel quad-band bandstop filter. It is formed by loading a microstrip line with two special resonators. The special resonator can be seen as a coupled-line and shorted stub-loaded half-wavelength microstrip resonator (CSSHMR). The resonator can resonate at four frequencies, which forms the corresponding equivalent shorted points at the microstrip line. Therefore, signals are rejected at these equivalent short-circuited points, which realizes the quad-band bandstop responses. The four resonant frequencies can be separately adjusted in a limited range. The gap coupling between the resonators can be introduced to adjust the performance. A transmission line model is built to analyze the quad-band bandstop filter. A prototype quad-band bandstop filter is designed, fabricated and measured. The measured and simulated results have a good agreement.
In this letter a novel microfluidic reconfigurable filter is presented at 1, 1.4 and 1.8 GHz. This triple band filter is based on dual-mode ring resonators where metal-liquid switches are used for interconnection of different resonators and feed lines, therefore, allowing tuning of its center frequency as well as of its external Q. Simulated and experimental results are shown with good agreement.
In this paper, a compact printed monopole antenna for multiband communication application is designed and investigated. The multiband functionality is achieved by the combination of a rectangular radiating element with a pair of symmetrical meandered resonators.The proposed antenna works efficiently (>86%) with an optimally matching (VSWR<2) and adequate gain in the desired frequency bands centered at 4.27 GHz, 4.85 GHz and 6.45 GHz respectively. The prototype of the antenna is fabricated to validate effectiveness of the proposed design. A good agreement between simulated and measured results is observed.
A compact stepped-impedance dipole antenna with harmonic suppression is presented. The antenna occupies an overall size of 40 x 12 x 1.6 mm3 when being printed on a substrate with a relative dielectric constant of 4.4 and loss tangent 0.02. The simulation and experiments are well matched and offer a 2:1 V SWR (S11 < -10 dB) bandwidth of 590 MHz at 2.45 GHz. In comparison with a conventional strip dipole, the stepped impedance based dipole antenna shows complete suppression of the first and second harmonics making it suitable as an efficient EMI emission free antenna for widely used Bluetooth and WLAN applications. It can also be employed for wireless power transfer applications with more efficiency.
In this letter, a compact microstrip bandpass filter (BPF) with four transmission zeros (TZs) is designed by using a short-stub centered loaded folded dual-mode resonator and an I/O mutual coupled open-stub loaded feedline structure. The coupling structure can realize source-load (S-L) coupling with quadratic function coupling coefficient, which can generate three TZs in the upper-stopband to improve the selectivity. Owing to the intrinsic characteristics of the dual-mode resonator, one extra TZ can be created near the lower passband edge. Finally, a compact BPF with fractional bandwidth (FBW) of 3.5% located at 2.4 GHz for WLAN application has been designed and fabricated. Good agreement between simulation and measurement verifies the validity of the design.
This letter presents a novel differential filtenna for microwave systems at 2.4 GHz on planar technology. This filtenna exhibits 5% bandwidth with a 3-pole Chebyshev response. The filtenna uses a square patch as radiating element combined with λ/2 resonators. Experimental and simulated return losses are presented with good agreement. Moreover, the experimental common and differential mode radiation patterns are presented showing an attenuation greater than 15 dB for the common mode.
A modified compact microstrip resonance cell (CMRC) low pass filter (LPF) with ultrawide and deep stopband using novel fractal patches is presented. The proposed filter has low insertion loss in the passband, good selectivity, ultrawide and deep stopband. The experimental results show a 3-dB cut-off frequency of 2.85 GHz and out-of-band rejection up to 67 GHz with 181.5% relative stopband bandwidth.
In this paper an ultra-wideband band (UWB) pass filter is introduced. The filter is composed of multiple shorted shunt stubs and defected ground structure (DGS). The defected ground structure is composed of some circular-shape defects and diagonal-line patterns. The bend-shaped defected-ground structure is thoroughly studied and compared to some other defected structures. The filter features a simple structure and small dimensions (12 × 22 mm2). Meanwhile, a systematic design method is presented. The analysis method is based on numerical methods and is verified by a commercially available EM simulator. The 3 dB passband of the proposed wide band filter is between 2 GHz and 10 GHz.
This paper describes the design of a broadband, fixed-IF, high efficiency single subharmonic mixer at Ka-band. The co-simulation between HFSS and ADS is applied to the modeling of the mixer. In order to improve the accuracy of simulation, the diode model is divided into passive linear model and active nonlinear model. On this basis, a global accurate equivalent circuit model of mixer is proposed and verified by testing data. The circuit of the presented mixer printed on the substrate of Rogers RT/Duroid 3003 is mounted in a waveguide block. When the fifixed IF frequency is set at 1.5 GHz, measured results show that the conversion loss is less than 8 dB over the RF bandwidth from 25 GHz to 39 GHz with 12 dBm of local oscillator power. The minimum conversion loss of 6.2 dB is measured at 28 GHz. The measured isolation between LO and IF, LO and RF is over 23 dB. The measured isolation between IF and RF is over 20 dB. Good isolation is achieved.
A cavity-backed crossed bowtie dipole antenna for wideband circularly polarization (CP) is proposed in this letter. By introducing four inverted L-shaped parasitic elements with sequentially rotated angles, two extra CP modes areexcited, thus greatly broadening the 3-dB Axial-ratio (AR) bandwidth (BW) of the antenna. The proposed antenna is simulated, fabricated and measured. Results show that the antenna generates a 10-dB impedance bandwidth (IBW) of 91.4% (1.2-3.22 GHz) and a 3-dB AR bandwidth of 74.1% (1.37-2.95 GHz). In addition, the antenna achieves a unidirectional radiation pattern with a stable gain of 6.52-9.27 dBi over the whole CP operating band.
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