A direct 61 GHz demodulator, based on a rectangular waveguide (WR-12) six-port, is presented in this letter. The six-port device, composed of four 90° hybrid couplers fabricated in a metal block of brass, is implemented in ADS software. Good agreement between QPSK demodulation results using an ideal six-port model and a second one, based on the S-parameter measurements of a 61 GHz hybrid coupler, is achieved.
A hemisphere dielectric resonator pattern reconfigurable antenna (DRA) is proposed in this paper. The proposed antenna element can operate in four states (SI~SIV) and correspondingly reconfigures its patterns in four directions. A thinning linear array by non-uniform spacing with the element is constructed to scan its main beam from θ=-77o to 77o in E-plane with 3-dB beam coverage from θ=-90o to 90o by changing two states and progressive phases.
A fabricated multilayer low-temperature co-fired ceramic (LTCC) delay line (approximate 16λg at 9.5 GHz), using 3D meander strip line, is proposed in this paper for the first time. The advanced quasi coaxial ground vias (QCOX-GND vias) are proposed for signal vertical interconnections in this multilayer structure. These technologies obtain good performances in the whole band (9~10 GHz). Measurement results show that, besides low insertion loss and low VSWRs, low time dispersion can be achieved as ≤±0.002 ns, which is very important to a delay line. The more compact size, as 8 mm × 10 mm × 2.37 mm, can also be obtained than other delay line structures.
A dual-band printed dipole antenna with integrated balun feed is given in this paper. First, the fork-shaped slot is etched on the arms of the printed dipole antenna to achieve the dual-band operation with resonances at WLAN bands. The radiating element without balun is optimized and operates at 2.4 GHz (2180-2750 MHz) and 5.2 GHz (5040 MHz-5480 MHz) where return loss is less than -10 dB. In order to further get a lager bandwidth, a modified Marchand balun is introduced for dual-band operation, which can provide two resonances in each band to enhance impedance bandwidth. By co-designing the radiating element with the dual-band balun, an antenna covering 2150-2750 MHz and 5050-6230 MHz has been achieved. The design equations for modified balun have been presented and agreement between calculations and measurements is good.
This paper describes a memory-reduced (MR) compact two-dimensional (2-D) order-marching time-domain (OMTD) method for full-wave analyses. To reduce memory requirements in the OMTD method, the divergence theorem is introduced to obtain a memory-efficient matrix equation. A lossy microstrip line is presented to validate the accuracy and efficiency of our algorithm.
A novel CPW-fed antenna having a frequency band-notched function for UWB applications is proposed and studied. By inserting a pair of inverted-T-shaped slots on the radiation element, the narrow frequency band notch has been created to cover the desired frequency varying from 3.4 to 3.69 GHz and the required UWB bandwidth is also acquainted. Good monopole-like radiation patterns and antenna gains have also been obtained.
A configuration for a miniaturized band-pass filter on a coplanar waveguide (CPW) is proposed in this communication. Parametric studies conducted for various geometrical parameters suggest that the frequency response of the filter is strongly related to that of the spiral slots. But a series gap on the center conductor of the CPW changes the overall response of the device For validation of these concepts, a bandpass filter operating at about 3.5 GHz has been designed, fabricated and tested. Experimental results show good agreement with electromagnetic simulations. The design for a microwave laminate shown here requires an area of approximately 0.1λ0 x 0.1λ0.
A novel set of boundary conditions requiring vanishing of the normal components of the D and B vectors at the boundary surface was introduced recently and labeled as the DB-boundary conditions. Basic properties of a resonator structure defined by the spherical DB boundary are studied in this paper. It is shown that the resonance modes polarized TE and TM with respect to the radial direction coincide with those of the respective PEC and PMC resonators. Modes in the DB resonator show higher degree of degeneracy than those of the PEC resonator which may find application in materials research.
In this work, we propose to use a type of periodic structures, the soft surfaces in their planar version, to reduce the back radiation of patch antennas. A key aspect of these surfaces when compared to other periodic structures is their anisotropy which provides different behaviour for different field polarization (horizontal or vertical). This make them especially convenient for this application, as the soft surfaces force the field intensity for any polarization to be zero on the surface for waves propagating along the surface. In this paper, a design example is presented and the back radiation reduction by using planar soft surfaces is demonstrated.
According to the Coarse Wavelength Division Multiplexing (CWDM) wavelength dependent transmission characteristics, a wide range fiber Bragg grating (FBG) demodulation method is proposed and experimentally demonstrated in this paper. The relationship between system input and output is obtained through analysis, and verified experimentally. Particularly the influence of light source power on demodulation precision and calibration value is analyzed. The wavelength demodulation range of the system is about 10 nm, which can realize the measurement of 8000με; The precision can be 3~5 pm. Since the system is compact, low cost and passive, it is able to be integrated as a portable demodulation module.
An externally modulated NTSC 77-channel erbium-doped fiber amplifier (EDFA)-repeated system employing Fabry-Perot (FP) etalon at the receiving site to improve system performance was proposed and demonstrated. In comparison with conventional externally modulated fiber optical CATV transport systems, good performance of carrier-to-noise ratio (CNR), composite second order (CSO), and composite triple beat (CTB) were achieved for the full channel band over a 100-km single-mode fiber (SMF) transmission. Our proposed systems are suitable for the long-haul fiber optical CATV transport systems.
A bidirectional high gain four-element printed dipole array for WLAN (2.4/5.8 GHz) applications is analyzed and successfully implemented in this paper. Each element used is a double-side printed dipole fed with a balance twin-lead transmission line. A wide-band balun is implemented for the dipole array. Both simulated and measured data are pretty matched. According to the measured results, the bandwidth with return loss less than -10 dB is about 280 MHz (2250-2530 MHz) and 510 MHz (5470-5980 MHz) in the two operating bands, the measured gain for 2.4 GHz band is between 4.5 and 5.9 dB, and 6.1-8.9 dB for 5.8 GHz respectively. Good shaped patterns have also been attained by tuning parameters of the dipole array.
In this letter, we use two embedded isolation moats which have different size to obtain the wide stopband elimination performance. The proposed structure is realized by embedding the double isolation moats between power and ground planes. The suppression frequency range of the proposed structures is from 1.2 to 7.2 GHz and the peak noise improvement in time domain is 36%. Furthermore, the proposed structure uses two elimination cells to avoid the parasitic effect generated in the frequency range of several hundred MHz.
Bootlace lens is the most appropriate choice for multiple beam forming. A compact symmetric bootlace lens has been developed. Here, a theoretical modal is developed which predicts the primary amplitude distribution across the array port of the lens. Amplitude distribution depends upon the gain performance of array contour of the lens. This theoretical modal develops a symmetric bootlace lens without complex analysis.
This paper presents a numerical and experimental analysis of a horizontally polarized HF antenna?The antenna is aimed to be compact, wideband and high power gain. A V-shape wire-structured pentagonal antenna has acceptable performance in both aspects of gain and VSWR. The V-shape structure yields a comparatively high gain relative to the 27 m radiation arms. By incorporating both ground-loaded guys and convex pentagon-shape arms, the antenna can cover the whole HF band. The measured and simulated results show that the VSWR of this antenna is within 2.55:1 over 3~30 MHz and the average power gain is about 11 dBi.
A planar Dual Exponentially Tapered Slot Antenna(DETSA) is presented in this paper. The DETSA is simulated and designed with the sofware Ansoft HFSS. The dimensions of the antennas and the exponential functions of tapered slot are also described. To verify the design, the DETSA is fabricated and measured, good impedance matching over a very wide bandwidth is achieved, measured radiation patterns of the proposed antenna is compared with the simulated one, good agreement is observed.
A novel composite right/left handed transmission line is presented which is synthesized by etching Koch fractal shape slot in the ground plane and series capacitive gap in the conductor strip. Unlike the structures loaded with complementary split ring resonators (CSRRs), the proposed structure can operate at very wide band and is used to design an ultra-wideband (UWB) filter. The UWB filter is fabricated and tested. The relative bandwidth of the -10 dB return loss is 128% and the insertion loss is larger than -1.5 dB except at high frequencies. The equivalent circuit model of the proposed structure is presented and the electrical parameters are also extracted. The circuit model results are compared with the simulation and measurement results which verify that not only the extracted parameters are exact but also the equivalent circuit model is reasonable.
A multifunctional meander line polarizer is described. The polarizer is capable of effecting conversions between linear and circular polarization and between left-hand and right-hand circular polarization. It can also cause arbitrary rotation of linear polarization, including converting a wave from horizontal polarization to vertical. The polarizer is analyzed by the spectral domain approach.
A compact printed dipole antenna for UHF RFID reader is presented. The proposed antenna occupies a volume of 65*30*2 mm3 and the radiator is composed of two rectangular patches etched with folded slit. The radiation element of the dipole antenna is fed by 50 Ω coaxial line. Measured results indicate that the proposed antenna has a good impedance matching characteristic at 905-935.5 MHz (return loss less than 10 dB). In addition, the effect of some parameters on the performance of the proposed antenna is also discussed in this article. This printed dipole antenna will be applicable for future RFID systems.
Based on the broadside-coupled split-ring resonator (BC-SRR), a tunable left-handed metamaterial (LHM) was proposed in this paper. The two rings of BC-SRR are etched on two separate substrates so that the coupling between the two rings can be adjusted by slightly slip one of the two substrates relative to the other one. Thus, the magnetic resonance frequency of the modified BC-SRR can be tuned. By combining the modified BC-SRR (MBC-SRR) with continuous conducting wires, a tunable LHM can be realized. The tunable LHM can realize both rough and minor tunings by minor slips along and perpendicular to the gap direction of BC-SRR, respectively. The proposed tunable LHM has many potential applications in microwave devices.
A compact ultra-wideband (UWB) monopole antenna with four-band-notched characteristics is introduced in this paper. The proposed antenna can achieve four-band rejection at 3.4, 5.5, 8 and 11 GHz with desired bandwidths only using one novel structure called nested complementary split-ring resonator (CSRR) which is etched inside the ground plane. This method used to obtain four-band-notched characteristics is firstly proposed in this paper. The antenna has a small dimension of 35*27mm2. The VSWR and radiation patterns of the fabricated antenna are presented, which prove that the designed antenna is a good candidate for various UWB applications.
In this paper, we present an efficient hybrid spatial-spectral formulation of the method of moment (MoM) in conjunction with the Mixed-Potential Integral Equation (MPIE) for planar circuit analysis. This method is based on the decomposition of the Green's functions in two parts: quasi-static in the near field region and the dynamic contribution in the far field region. Using this decomposition of Green's functions, the method of moment matrix entries can be reduced and expressed to a sum of two integrals. The first one is expressed in the spatial field and corresponds to the quasi-static contribution. It is analytically evaluated after a development in Taylor series of the exponential terms in the function to integrate. The integrals expressed in the spectral field and corresponds to the dynamic part have the advantage of being calculated on a finite range and this independently of the choice of the basis and test functions. The integrals expressed in the spectral field are performed by using numerical integration. It is also demonstrated that this hybrid method has accelerated the matrix fill in time by using a Fast Fourier Transform (FFT) algorithm. In order to validate the proposed method, numerical results are presented.
A novel printed monopole antenna for ultra-wideband (UWB) applications is presented, which is composed of wide slot and Y-shaped microstrip feed line with a pair of inverted-L-shaped notches. The prototype with an overall size of 26 mm × 30 mm × 2 mm achieves good impedance matching, constant gain, stable radiation patterns, and a relative impedance bandwidth of 110.6% is achieved, which covers 3.09-10.74 GHz.
A thermal analysis and structure of a ridge single mode waveguide with a metal heater are presented. The steady-state temperature increases linearly and the thermal response becomes slower at the same power consumption, when the under-etched depth in the lower cladding increases. When the upper cladding thickness decreases, the thermal response becomes faster. This shows that a thinner upper cladding and a deeper etching are preferred to achieve a faster thermal response and lower power consumption, respectively. The numerical simulation also shows the power consumption of the present ridge waveguide is almost third of that for conventional one and the response time is half of that of the conventional one.
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