A low-profile planar monolayer antenna for ultra-wideband (UWB) operation is presented. To achieve a UWB performance along with a compact size, a hybrid square-circular radiator and a rectangular open slotted ground plane with two symmetrical I-shaped tuning stubs are proposed. The antenna is fed by a coplanar waveguide line and has a small size of 44 × 32 × 1.6 mm3. The prototype of the proposed antenna was fabricated and tested in an anechoic chamber. The simulated and measured results show good agreement over the entire ultra-wide bandwidth. The measured results indicate that the proposed antenna can provide a wide impedance bandwidth of more than 154% from 1.7 to 13.3 GHz with -10-dB reflection coefficient. In addition, it is demonstrated that by introducing several antenna designs, the impedance bandwidth can be improved from 43% to 154%. Besides several mechanical advantages, such as compact in size, easy fabrication, and monolayer configuration without any back ground plane, the proposed antenna also shows a good performance in its radiation characteristics and time-domain behaviors. The measured results in both frequency and time domains prove that the proposed antenna can be used in a wide range of UWB applications.
A MMW/IR compound Cassegrain antenna system for mono-pulse radar applications is presented in this paper. By comparing different modeling methods of conformal frequency selective surface (CFSS), a sub-reflector, with a good performance of reflection at 93 GHz and transparency at the wavelength of 1.06 μm, is achieved according to sputtering technique. At the wavelength of 1.06 μm, transmittance of the sub-reflector is 67%. Compared to a Cassegrain antenna system consisting of a metallic sub-reflector with identical size, the gain of the compound antenna system has a negligible loss (less than 0.4 dB) at 93 GHz. Compared with the patent in [13], the design can improve the limited size of receiving system and the utilization of aperture of the compound detection system at IR region, and can also enhance the heat dissipation.
A wide beam, circularly polarized (CP) antenna is presented for satellite communications. The antenna consists of two crossed bent dipoles, two baluns and two pairs of rectangular patches. The two dipoles are fed by the two baluns, respectively. The arms of the dipoles are bent to save the horizontal space and to broaden the beamwidth. The rectangular patches which are connected to the arms of the dipoles form the matching structure of the proposed antenna. The impedance bandwidth of the antenna is broadened by adjusting the length of the rectangular patches. A broadband 90° power divider is used to feed the proposed antenna and to realize circular polarization. The antenna has a -10-dB impedance bandwidths of 77% (1.73-3.89 GHz). The proposed antenna exhibits a measured 2-dB AR bandwidth of 76.3%, from 1.71 GHz to 3.8 GHz. The 3-dB beamwidth is greater than 88°over the whole working band. Results show that the proposed antenna is suitable for the application of satellite communications.
In this article, a compact planar inverted-F antenna with a wide frequency band for WLAN, Bluetooth, HiperLAN, LTE2500, and WiMAX applications in mobile handsets is proposed. The designed PIFA provides two operating bands at 2.5 GHz with a bandwidth of 300 MHz (13%) and at 5.2 GHz with a bandwidth of 5700 MHz (76%). The dual-band performance and the improved bandwidths are realized by two techniques: the integration of a T-shaped slot in the radiating patch of the antenna and the addition of two elements in the side of the PIFA. The two operating bands of the antenna are controlled by adjusting the size of slot and the size of elements 1 and 2. The distribution of the specific absorption rate (SAR) of 1-g and 10-g in the head of human tissues for two positions of the antenna at 2.5 GHz and 5.2 GHz is also studied. The results of simulation and measurement of the proposed antenna are presented and discussed.
A broadband substrate to substrate microwave circuit interconnection is proposed using bond wires and defected ground structure (DGS). The proposed square-shaped DGS etched under compensated microstrip open stubs not only expands its operating bandwidth, but also increases the characteristic impedance of microstrip line without narrowing its width, which breaks the PCB fabrication limitation of narrow stubs. The proposed structure can make the impedance of the microstrip line much larger than that without DGS. A 250 Ω characteristic impedance is easily achieved using 0.6 mm microstrip line with the proposed DGS. Measured S21 and S11 of the proposed interconnection are better than -0.8 and -15 dB from DC to 38 GHz, respectively. And a bandwidth increment of more than 1200% is achieved compared with the conventional one.
A compact magnetic Yagi antenna and a four-element array with vertically polarized radiation are presented using the substrate integrated waveguide (SIW) technology. The SIW functions as driven element to generate vertically polarized wave. Microstrip patches are connected to ground plane function as magnetic dipole directors. With this arrangement, a compact magnetic Yagi antenna with vertically polarized radiation is designed. The total area is only 1.58λ1×0.95λ1 (λ1 represents the wavelength at 9.5 GHz) and reduced by 63.1% compared to previous magnetic Yagi antenna. The relative bandwidth is 16.15% and peak gain 7.31~8.82 dBi. Then the four-element linear array is analyzed, fabricated and measured. Simulated and experimental results demonstrate that the array antenna still preserves vertical polarization, and the peak gain is 14.06~14.78 dBi in the relative bandwidth of 14.43%.
In this paper, a novel compact band pass filter (BPF) is proposed for Global Positioning System (GPS) receivers. The proposed BPF configuration is composed of a low pass filter (LPF) section formed by the coupled line transformer connected with a radial stub and two short circuited stubs embedded within the 50 Ω microstrip line connecting the input/output (I/O) port of LPF. The lumped equivalent model of proposed BPF is also presented and analyzed. Simulation as well as experimental results shows very good in-band (pass-band) and out-of-band (≈ 7fc (centre frequency)) characteristics. The 3 dB fractional bandwidth (FBW) is 3.2 % of fc, thus satisfying the GPS receiver requirement and the minimum insertion loss (IL) in pass-band is 1.28 dB.
In this manuscript, a reduced size, ground slotted monopole antenna, operating in the range of 3.1-10.6 GHz is designed and implemented for breast cancer detection using time reversal MUSIC. A homemade breast mimicking phantom has been experimentally designed to facilitate the detection implementation. The simulated and measured results are in good agreement. The slots and blending edges of the ground, along with the feed step are some techniques applied to the designed antenna in order to achieve a broad bandwidth and reduce considerably the reflection coefficient. The resulting dielectric constant from the breast phantom is relatively close to the real normal breast tissues. After the design has been completed, some techniques of time reversal MUSIC were employed to mimic the breast cancer detection. The experimental results show that both temporal and spatial images of the cancer (tumor) are well represented here.
A systematic procedure is presented for synthesis of generalized Chebyshev lossy bandstop filters with nonparaconjugate transmission zeros. From a lossy scattering parameters with the prescribed reflection zeros, the transformation formulas from the scattering matrix to the admittance matrix are obtained by reconstructing the non paraconjugate transmission zeros as paraconjugate ones. The canonical transversal array is modeled by partial fraction expansion of the normalized admittance functions, resulting in an increased order of the final network provided there are nonparaconjugate transmission zeros. The methods are simpler and more general than the ones in the literature. So it shows great versatility, and can also accommodate lossless network or a transfer function with symmetrical transmission zeros. To illustrate the proposed synthesis procedure, three typical examples have been carried out to validate the synthesis method.
This paper presents a new implementation technique of transmission zeros in an in-line coupled filter. Neither cross couplings between non-adjacent resonators nor separate side-line resonators have been used. Instead a mixture of single-mode hairpin resonators and dual-mode patch resonators have been adopted in a bandpass filter with one asymmetric transmission zero. The introduction of the patch led to an improved frequency selectivity through an independently controllable transmission zero. This approach has been verified by a three-pole filter at 2.6 GHz with 8% bandwidth and a transmission zero at 2.4 GHz. Good agreement has been shown between the measurements and the simulation.
This paper presents dielectric resonator antennas (DRAs) as efficient energy harvesters in the microwaves regime. A single DRA and 1×3 array were used to build foundation profiles for DRAs as energy harvesters. The proposed structures were designed and fabricated to resonate around 5.5 GHz. The study examined different factors that affect the harvester power efficiency. The size of ground plane and coupling between dielectric resonator (DR) elements in an array were studied, highlighting their effects on the overall efficiency of the harvester for different incident polarizations. A 5×5 array was built based on the studied factors and tested numerically and experimentally. Measurements showed that energy absorption e ciency as high as 67% can be achieved using an array of DR antennas.
This paper presents the design and experimental research of a high efficiency balanced frequency tripler in the whole Ka band incorporating compensation solder pads. An anti-parallel GaAs Flip-Chip varistor diode is applied in this frequency tripler. The frequency tripler has the advantages of low conversion loss, broadband and compact circuit size. Considering the parasitic parameters resulted by the actual pads of the nonlinear device, a compensation solder pad was developed and adopted. The conversion loss of the frequency tripler is 15 dB with variation of ±1 dB across the output frequency from 30 to 37.5 GHz. In experiment, the maximum output power of 5.8 dBm is obtained at 35.4 GHz with 3.8% conversion efficiency when the input power is 20 dBm, and the 3-dB operation band width is about 10 GHz, which shows a good agreement between the simulation results and the experimental results.
In this paper, a new antenna is designed in order to use in the wireless capsule endoscopy (WCE) system. This antenna consists of two parts; the small monopole part and the small spiral. Having the omnidirectional radiation pattern for covering the stochastic motions of the capsule into gastrointestinal and also, appropriate gain and wide bandwidth to achieve high resolution images must be considered in designing procedure. In this design, a good radiation pattern is obtained from small monopole, and using the spiral structure leads to an appropriate wide bandwidth and a miniaturized antenna. By simulating this antenna in the human body environment and considering four different body tissues and their results, the antenna has the bandwidth of 360 MHz (39.3% relative bandwidth) at 928 MHz center frequency which covers the ISM band (868.0-868.6 MHz and 902.8 to 928.0 MHz). The radiation pattern of the antenna is omnidirectional. The maximum gain of the designed antenna is -23 dB, over the frequency band that is suitable for using as a transmitter antenna in the WCEs.
Based on gain optimization methods, superdirective beamformers can achieve high beam directivity with small aperture array. However, the extreme sensitivity to array uncertainty is a main obstacle to engineering application. In this work, a robust gain optimization algorithm under uncertainty set constraint is proposed. Considering steering vector mismatch is the result of combined effect of various array errors, and it is a measurable indicator especially in receiving system. We apply its uncertainty as a constraint on gain optimization method, which is more intuitive in physical sense. Different from existing solutions, it makes a better tradeoff among directive gain, robustness and radiation efficiency. Experimental analysis verifies its good performance in engineering.
A capacitively fed rectangular patch antenna for anti-metal RFID tag was studied. It was found that by using capacitively feeding and a thin micro-strip line, the input impedance could be stabilized with respect to ground plane size. As a result, the reading range degradation was avoided, and the presented antennas have almost the same reading range when used on metal or non-metal objects. The mechanism was explained by a basic antenna design and a transmission line model. Then a more practical compact design having much smaller size was presented. Prototypes of both the basic design and the compact design were fabricated and tested. The testing results validated the effectiveness of the designing method.
A novel wafer level integrated low-insertion-loss filter working at 1.8 GHz (DCS LPF) with suspended inductors and patterned ground shields on the lossy silicon substrate is fabricated. Thick BCB interlayer is used as the supporting dielectric, and the backside cavity on Si wafer is formed by using a two-step back-etching process. The influence of patterned ground shields on the Q factor of the suspended inductors and the influence of low-resistivity silicon on the insertion loss of filters are analyzed by EM simulation. The fabricated 2.7 nH inductor has a maximum Q factor of 49 at 8.2 GHz and high Q factors more than 22 in the broadband frequency range from 1 GHz to 10 GHz. And the realized LPF in DCS band has the insertion loss of 0.35 dB and return loss of more than 15.5 dB at the pass band, with the second harmonic rejection being 23 dB and the third harmonic rejection being 38 dB respectively.
This paper introduces a new volumetric conical notch-band antenna. Structure of this antenna is in contrast with planar and printed band rejection antennas currently existing in almost all of the literatures. The radiation pattern of the proposed antenna is symmetrical and stable against frequency variation, while planar and printed antenna types suffer from high variation of their radiation pattern with frequency, and consequently asymmetric and unstable omnidirectional behavior. The frequency band of the antenna is notched with two slots implemented on the antenna structure. Uniform various frequency band rejections are achieved by changing the slots dimensions and position. Both measured and simulation results of manufactured antenna show the frequency bandwidth of the antenna is from 3 to 4.9 GHz and from 6.2 to 11 GHz with reflection coefficient less than -10 dB. Moreover, the antenna notches the frequency band from 4.9 to 6.2 GHz with nearly uniform reflection coefficient level of approximately -3 dB. Stable radiation pattern and proper range of frequency band rejection make the designed antenna an appropriate candidate for the use in UWB and indoor communication systems.
Evanescent mode substrate integrated waveguide (SIW) is one of the promising technologies for design of light-weight low-cost microwave components. Traditional realization methods used in the standard evanescent waveguide technology are often not directly applicable to SIW due to dielectric filling and small height of the waveguide. In this work, one of the realization methods of evanescent mode waveguides using a single layer substrate is considered. The method is based on the use of coaxial stubs as capacitive susceptances externally connected to a SIW. A microwave filter based on these principles is designed, fabricated, and tested. The filter exhibits a transmission zero due to the implemented stubs. The problem of evanescent mode filter analysis is formulated in terms of conventional network concepts. This formulation is then used for modelling of the filters. Strategies to further miniaturization of the microwave filter are discussed. The approach is useful in applications where a sharp roll-off at the upper stop-band is required.
A novel multi-band cylindrical dielectric resonator antenna (CDRA) using microwave laminates with permittivity variation in azimuth direction fed by coaxial probe is proposed in this paper. The proposed structures are constructed using different materials having different permittivities in azimuth direction in cylindrical dielectric resonator (DR). In order to determine the performance of various design parameters on resonance frequency and bandwidth, parametric studies have been performed. The operating band can be scaled up or down by adjusting the design parameters. Dualband and triple-band CDRAs have been fabricated using commercially available microwave laminates to validate the simulation results. For each case, the input reflection coefficient, radiation pattern and antenna gain are simulated and measured. Good agreement between simulated and measured results has been observed. The proposed antennas may be suitable for WLAN applications.
We investigate the problem of near field interactions with general antenna systems using the antenna current Green's function formalism recently proposed by the authors as a framework for the theoretical and computational analysis of the interaction problem. The paper focus is on conceptual and numerical issues related to the analysis of the electromagnetic response of generic devices to arbitrary illumination fields produced, for example, by nearby source or scattered by surrounding objects. We provide some method of moment numerical examples involving wire antenna systems substantiating the ACGF approach to the problem of near field excitations.
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