This paper presents an effective analysis method for EBG reducing patch antenna coupling. A couple of coaxial probes are used to analyze the mutual coupling reduction range of patch antenna arrays loaded with EBG in this method. Conventional FDTD/PBC algorithm for EBG structures is appropriate only in infinite ground plane and substrate. The gained frequency band-gap by using the algorithm can not be directly used in finite ground plane because of the edge effects. While the proposed coaxial probe method is valid not only in infinite ground plane and substrate, but also for finite ground plane. The method is more suitable for real environments. In order to validate the described method, a two-element microstrip patch antenna array is fabricated and measured. The experimental results are in good agreement with the theoretical data obtained by using the proposed method.
In this paper, we investigate surface plasmon-polariton propagation at the interface of metal and magnetooptic dielectric semiinfinite layers where both layers are magnetized. Using magnetic group theory, we calculate scattering matrices for the waveguide sections with three orientations of dc magnetic field. Solving analytically the wave equation for the Voigt configuration, we obtain exact dispersion relation for this waveguide. Numerical examples show that the nonreciprocal phase shift between forward and backward waves can be increased significantly as compared with the case where only the magnetooptic dielectric layer is magnetized.
In this paper, a novel high selectivity dual-wideband microstrip bandpass filter (BPF) is proposed using two stub-loaded triple-mode stepped-impedance resonators (SIR) which are the same type but with different sizes. The SIR is formed by attaching one T-type open stub at the center plane and two identical short-circuited stubs symmetrically to stepped-impedance open microstrip line. And it can generate one odd mode approximatively determined by the stepped-impedance microstrip line and two even modes flexibly controlled by the loaded stubs. Either of the SIRs in this filter can not only separately generate one passband but also control the passband performance. Due to the intrinsic characteristics of the SIR, four transmission zeros can be created to improve the selectivity. A dual-wideband filter with the fractional bandwidth 14.9% for the first band from 3.09 GHz to 3.58 GHz and 10.2% for the second band from 4.99 GHz to 5.53 GHz is designed and fabricated. The filter is evaluated by experiment and simulation with good agreement.
A 50% size reduction of the rectangular dielectric resonator antenna (DRA) is achieved by introducing shorting posts at the edge of the DRA in this paper. By choosing proper height of the shorting posts, the radiation pattern in E-plane maintains almost the same shape as the conventional rectangular DRA. The cross polarization can also be controlled to be a relative low level. By adding an open stub in the feed line, the proposed antenna has almost the same resonant frequency with the conventional rectangular DRA. The measured results for the constructed prototype are also exhibited and discussed.
Reflectionless cylindrical concentrators have been designed up to now in an initially empty core space by applying forminvariant, spatial coordinate transformations of Maxwell's equations. We show that the reflectionless cylindrical concentrators in initially homogeneous and isotropic dielectric core media allow an enhanced concentration of the incident field. Designs of more complex reflectionless concentrators in initially inhomogeneous dielectric media represented by empty or dielectric-filled circular containers are also presented. The transformation equations are given explicitly, and the fields are expressed analytically. The functionality of these devices is illustrated by several examples.
In this letter, a novel compact broadband and high rejection bandpass filter (BPF) with the source-load coupling is proposed using the triple-mode stub-loaded resonator. The resonator is formed by attaching one T-type open stub at the center plane and two identical short-circuited stubs symmetrical to high impedance microstrip line. It can generate one odd-mode resonant frequency fm2 and two even-mode fm1, fm3 in the desired band. The fm2 can be approximately determined by the high impedance microstrip line. The short-circuited stubs and T-type open stub can be applied not only to separately adjust the fm1 and fm3 while the two other ones keep relatively stationary, but also to separately create transmission zero near the lower and upper cut-off frequencies, leading to a high rejection skirt. As a result of the source-load coupling, two transmission zeros in the upper-stopband are generated to deepen and widen the upper-stopband. A high rejection BPF with the fractional bandwidth 76% is simulated, fabricated and measured. The measured results agree well with the EM simulations.
A new dual-polarized horn antenna fed by a microstrip patch is proposed. The patch is excited in two orthogonal polarizations by small gaps between the patch edge and the microstrip open end. A horn antenna operating at 14.9 GHz is designed, fabricated and tested. Measurements show that the horn has a reflection coefficient of less than -10 dB, and a port isolation greater than 30 dB, over 14.6--15.2 GHz, and a gain of 12.34 dBi and 10-dB beamwidths of 87° and 88° at 14.9 GHz.
An innovative way to analyze the design of beam-forming networks (BFN) for scannable multi-beam circular antenna arrays using the CORPS (Coherently Radiating Periodic Structures) concept is introduced. This design of CORPS-BFN considers the optimization of the complex inputs of the feeding network by using the Differential Evolution (DE) method. Simulation results for different configurations of CORPS-BFN for a scannable circular array are presented. The results shown in this paper illustrate certain interesting characteristics in the behavior of the array factor for the scannable circular array. The most significant aspect that is unique to this proposal is the simplification of the feeding network based on CORPS.
An ultra-compact dual-band printed antenna is proposed. Connective and concentric double split rings (CCDSR) are used to generate two resonant frequencies in wireless local area network (WLAN) frequency bands. Tuning arms are added to the microstrip fed line, which can be used to tune the upper frequency band. The dimension of this antenna is only 9×24×1mm3, much smaller than those reported antennas. The measured -10 dB bandwidth in the 2.44GHz band is 140MHz (2.37-2.51GHz) and in 5.34GHz is 1.23GHz (4.86-6.09GHz), covering the 2.4/5.2/5.8GHz WLAN operating bands. Good radiations at these bands are also observed.
In this letter, for the very first time, triple band rectangular patch antenna loaded with metamaterial has been reported. Maximum directivities demonstrated here for all the three bands are quite high in comparison with previously reported any kind of rectangular patch antenna. This unique triple band performance has been achieved with the help of newly produced TM0δ0 (3<δ<4) mode, symmetric slot loading and parasitic patch adjustment. Application of etched slot and parasitic patch in DPS (double positive)-metamaterial juxtaposed layer loaded antenna has been also demonstrated for the first time. Considering the quite satisfactory performance (S-parameter, radiation pattern and radiation efficiency) of this novel design, we expect that our proposed ideas will be very effective to design all these metamaterial loaded novel rectangular patch antennas.
The Wave Concept Iterative Procedure is validated for multi-layered substrate with frequency dependent and negative index media. By shifting the plasma frequency, reconfigurable filter design is proposed with a center frequency tunability of 25%. Sensitivity to collisional plasma is proposed.
We experimentally characterize the pulse-shortening phenomena in traveling-wave field effect transistors (TWFETs). When a decreasing voltage pulse is applied to the gate line and an increasing voltage pulse is simultaneously applied to the drain line, a sinusoidal wave supported by an exponential edge is developed in the drain line. In order to make the velocity of the sinusoidal wave coincident with that of the exponential edge, the wavenumber of this sinusoidal wave must be considerably increased. Moreover, the small-amplitude parts of the wave disappear with the shorter propagation while the large-amplitude ones remain in the drain line. The input pulse is considerably shortened owing to these two properties. This paper validates the pulse-shortening phenomena by performing several measurements using a breadboarded TWFET.
A printed broadband planar inverted-F antenna (PIFA) with zeroth-order resonator (ZOR) loaded is proposed whose shorting strip of the PIFA is replaced by an inter-digital capacitor and thin inductive strip in series. The loaded inter-digital capacitor and thin inductive strip act as a shorting strip at the 3.1 GHz, which allows the antenna to maintain its regular performance. Around 2.0 GHz, the antenna with the inter-digital capacitor and thin inductive strip works on the zeroth-order resonance mode, which makes the physical size be independent of the wavelength. By merging the two modes, a broadband performance can be achieved. The size of the antenna is only 12.5 mm×7.81 mm×1.6 mm with single layer. The measured antenna bandwidth is 1.63 GHz (about 65%), total gain is above 2.5 dBi and the simulated radiation efficiency is over 90% in the working band. Especially the antenna has same direction of the radiation patterns in the broadband. In the end, the antenna with lumped elements loading is also discussed.
This paper presents a novel compact suspended double side millimeter bandpass filter (BPF) with wide stopband using Suspended Compact Microstrip Resonant Cell (SCMRC). For SCMRC exhibit slow-wave band-stop characteristics, two distributed SCMRC structures are designed to achieve wide stopband characteristic. By apply SCMRC structure and double side design, this novel BPF is size reduced. Back-to-back rectangular waveguide to suspended microstrip probe transitions at different millimeter bands are designed and fabricated to verify transmission characteristics of novel SCMRC bandpass filter. Experimental results show low insertion loss (< 1.2 dB) in the passband and sharp, wide rejection in the stopband with about 150% bandwidth (below -15 dB, from 50 GHz to 100 GHz), make good agreement with simulated results.
Metamaterial covers exhibit inimitable electromagnetic properties which make them popular in antenna engineering. A traditional metamaterial cover has an identical transmission phase for a normally incident plane wave regardless of its polarization state. The purpose of this research is to show the possibility of using a polarization dependent metamaterial cover to change the polarization state of the incident plane wave. Novel polarization-dependent metamaterial (PDMTM) covers, whose transmission phases for two principal polarizations are different, are presented. A full-wave FDTD numerical technique developed by the authors is adopted for the simulations.
Reflection from a planar DB interface placed in chiral and chiral nihility medium is studied. No difference between the two cases, regarding reflection chracteristics, is noted. No reflected backward wave is produced for DB interface placed in chiral nihility metamaterial. In this regard, DB interface may be considered as first known perfect reflector interface which yields non zero power when placed in chiral nihility medium.
This paper presents the synthesis of a novel dual-band bandpass filter with improved out-of-band performance. The proposed circuit is constructed by cascading a dual-band filter using trisection stepped impedance resonators (SIRs) and an L-C ladder lowpass filter using open-circuited stubs. The dual-band trisection SIR can provide the desired dual-band response, and the lowpass filter can improve the out-of band performance by suppressing the harmonics and spurious responses. The proposed filter has been fabricated and measured. Simulation and measurement results are found to be in good agreement.
By enabling both cavity modes and plasmonic resonance together in the designed two-handed metamaterial, we demonstrate a square-wave-like (SWL) bandpass filter with high-ratio bandwidth (HRB). Our results show that this metamaterial-based bandpass filter possesses high-ratio bandwidth of 30 GHz centered at 92 GHz, excellent transmittance beyond 87.5 %, sharp transition within 1.0 GHz from -3 dB to -20 dB as upper and lower band edge transitions, and dual-band behavior. Such an HRBSWL bandpass filter can be scalable and readily applicable for the commercialized unlicensed 60 GHz spectra with a bandwidth exceeding 7 GHz, solving the challenge of conventional passive bandpass filters to allow wide bandwidths and great quality factors simultaneously.
This paper presents a novel monopole antenna which uses split ring loading in order to achieve a dual-wideband operation for WLAN (2.4/5.2/5.8 GHz) application. By adjusting the split ring position and its natural resonant frequency, the proposed antenna can produce more than 1 GHz wideband match in the 5 GHz band. According to the measured results, the bandwidth with reflection coefficient less than -10 dB is about 715 and 1017 MHz in the two bands. Good radiation patterns are also achieved. The dimensions of the monopole loaded with split ring are 27.2mm×16.2mm×1mm, which is suitable for a hallway antenna or ceiling mount antenna of WLAN application.
In this paper, a triangular patch antenna (TPA) with 15°-75°-90° angles is studied. The simulation results, using the full wave simulator, IE3D, for this TPA shape are compared with those for the equilateral triangular patch antennas (ETPA), the right angle isosceles triangular patch antenna (RAITPA), the 30°-60°-90° TPA and 30o-30o-120° TPA. It is found that for the same resonant frequency, the 15°-75°-90° TPA occupies the least area among these triangular shapes. In an attempt to verify the simulation results, a 15°-75°-90° TPA operating at 900 MHz is designed, fabricated, and measured. The measured value for the resonance frequency is very close to the value obtained by simulation. Finally, a 15°-75°-90° TPA with a shorting pin is investigated. As expected, a miniaturized patch is obtained by loading a shorting pin at the tip of the patch.
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