This work presents a planar antenna for Ultra-High-Frequency (UHF) Radio Frequency Identification (RFID) Tags to be applied on metallic surfaces. The proposed radiating structure consists of a short-circuited patch antenna designed with a fractal geometry, resulting in a very compact and cost effective Tag. Showing a very good platform tolerance, such a Tag is also suitable for application on different kinds of materials (metal, glass, etc.).
In this paper, a complementary meander line split-ring resonator (C-MLSRR) model is proposed and its equivalent circuit model is given. Prototypes of microstrip lines loaded with C-MLSRR with and without series capacitive gaps are designed, which exhibit a negative permittivity behavior (without series capacitive gaps) and a left-handed behavior (with series capacitive gaps), respectively, at two different frequencies. The application of the C-MLSRRs in compact dual band (i.e., 2.52 GHz and 5.35 GHz) notch filter for wideband application is presented to highlight the unique features of the C-MLSRRs.
A repeaterless hybrid CATV/16-quadrature amplitude modulation (QAM) orthogonal frequency-division multiplexing (OFDM) transport system employing half-split-band and remote light injection techniques is proposed and demonstrated. Over an 80-km SMF transmission without optical amplification, good performances of carrier-to-noise ratio (CNR), composite second order (CSO), and composite triple beat (CTB) were obtained for CATV band; simultaneous high CNR and low bit error rate (BER) values were achieved for 16-QAM OFDM band. This architecture presents a feasible way to transmit both analog and digital video signals.
The non reciprocal effect of such devices as microstrip and coplanar isolators can be based on the field displacement phenomenon induced by a magnetized ferrite material. The structure under study is made from a ferrite thin-film deposited on a alumina substrate. A non symmetrical coplanar line is put on the ferrite film and the absorber is made from either a graphite film or a Tantalum Nitride film or a copper slab. In order to work in millimeter wave range the barium ferrite was selected. Moreover, the size of the component could be less than the circulator one. The small size and simple shape are the principal advantages of a coplanar isolator structure.
A 6:1 unequal Wilkinson power divider that combines the advantages of a coplanar waveguide with an electromagnetic bandgap (EBG CPW) and microstrip line structures suitable for a PCB circuit design is proposed. The highly characteristic impedance transmission line (TL) is realized by employing the proposed EBG CPW structure, which is difficultly achieved using the conventional microstrip line or CPW due to printed circuit board (PCB) process limitations. The proposed EBG structure enables the CPW line to have a very high characteristic impedance of over 207 Ω. The fabricated 6:1 power divider delivers excellent matching and isolation performances with more than 34 dB at 1.5 GHz. It also has exact dividing ratios of 8.46 dB and 0.7 dB at two output ports, respectively.
Brillouin fiber laser (BFL) is demonstrated using a piece of photonic crystal fiber (PCF) in conjunction with a Bismuth-based erbium-doped fiber (Bi-EDF) as the gain media with a simple ring resonator. The proposed BFL operates at wavelength of 1574.08 nm, which is 0.08 nm shifted from the Brillouin pump wavelength with a maximum peak power of 8 dBm. The BFL has a side mode suppression ratio and 3 dB bandwidth of approximately 23 dB and 0.02 nm respectively limited by the optical spectrum analyzer resolution. The BFL is also stable at room temperature and compact due to the use of only 20 m long of PCF and 215 cm long of Bi-EDF.
A perfect electric conductor placed in chiral nihility medium and excited by a uniform plane wave has been considered as an original problem. Using fractional operators, solutions to Maxwell equations which may be regarded as intermediate step between the original solution and dual to the original solution are determined. Each fractional operator is composed of fractional curl operator. As more than one dual to original solution exists, so in each case, corresponding impedance of the fractional dual reflector has been determined.
The conventional perfectly matched layer (PML) absorbing boundary condition is shown to be unstable when it is extended to truncate the boundary of the double negative (DNG) medium. It is a consequence of the reverse directions of the Poynting and phase-velocity vectors of plane waves propagating in such material. In this paper, a modified uniaxial PML (UPML), which is stable for the DNG medium, is derived. The auxiliary differential equation technique is introduced to derive the discrete field-update equations of DNG-UPML. Numerical results demonstrate the effectiveness and stability of the new UPML for the DNG medium.
While a geostationary weather radar would enable unprecedented monitoring of hurricanes and other severe weather, surface clutter could seriously limit its performance. The large incidence angles necessary for wide-area coverage, combined with the footprint size could cause surface clutter to obscure atmospheric return up to several km above the surface. The authors describe a Doppler filtering approach to clutter suppression and show simulation results. They find that Doppler filtering can significantly reduce the surface return, bringing surface clutter to acceptable levels. The authors then consider this approach when a staggered pulse repetition frequency is used to improve the maximum unambiguous velocity. They find that a method previously developed for ground-based weather radars can be successfully applied.
A compact three-layer shared-aperture dual-band dual-polarised sub-array operating in L/C-band is designed for application in synthetic aperture radar (SAR). Square, aperture-coupled patches in the C-band and a square, perforated L-band patch are combined on the top layer. They are fed from behind the ground plane by a combined feed system. Combined layers of patches and feed layers results in a highly compact antenna suitable for low weight applications such as space borne synthetic aperture radars (SAR).
In this paper, the inter-digital capacitance loaded loop resonators (IDCLLRs) are proposed to design microstrip band-reject filters. The analyzed structures are based on the coupling of IDCLLRs to a conventional 50 Ω microstrip transmission line. We have firstly studied the frequency response of one-stage IDCLLR-loaded microstrip transmission line. The main fratures of the IDCLLRs are small dimensions (much smaller than the wavelength at resonance) and more structural parameters (provide flexibility in design); Then a 6-stage IDCLLR-based microstip band-reject filter was designed and fabricated, it performs relative rejection bandwidth of 8.1% and rejection level of 23 dB. This stop-band is resulted from presence of the artificial medium with negative effective permeability (μeff<0). In addition, it is easy to control the rejection bandwidth by only employing different length of inter-digital fingers (for multiple tuning). A 9-stage band-reject filter with multiple tuned IDCLLRs has been fabricated and tested, its relative rejection bandwidth is extended to 11.5%. Simulated and measured results are presented.
A lowpass filter with a very sharp transition band using defected ground structures (DGS) is described. The lowpass filter was designed by using three dumbbell slots at the ground plane. Two of those dumbbell slots are the reshaped rectangular and the third dumbbell slot is an inverted triangle. The lowpass filter esigned at cutoff frequency of 3.0 GHz, which is suitable for GSM900, GSM1800 and UMTS applications of the mobile communications. The equivalent circuits for the proposed lowpass filter and its corresponding LC parameters are given. The proposed lowpass filter provides a size of 33x30 mm2, and have good transition band with good performance in the passband and have wide rejection up to 9.25 GHz plus harmonic suppression in the stopband. Measurements results show good agreements with the simulated results.
Thresholded Landweber Iteration (TLI) is an attractive algorithm since it has the advantage of simplicity for the problem of sparse reconstruction. However, this algorithm depends heavily on the coherence property of the redundant ictionary, and its convergence rate is slow. In this paper, we develop a modified version of TLI by using a sensing dictionary. The proposed algorithm significantly improves the reconstruction performance and the convergence roperties when compared to the classical TLI. We provide a sufficient condition for which the modified TLI algorithm an be guaranteed to exactly identify the correct atoms and also discuss the convergence properties for this agorithm. Finally, simulation results are presented to demonstrate the superior performance of the proposed lgorithm.
The complex permittivity and permeability of barium hexaferrite in the 8-12 GHz range was determined by using perturbation of electromagnetically coupled Ag thick film patch antenna due to overlay. In this technique even minor change in the overlay material properties changes the antenna response. The power gain of the EMC patch antenna was enhanced by 50% due to barium hexaferrite overlay. Barium hexaferrite was synthesized by co precipitation method and their fritless thick films were fabricated by screen printing technique. The properties were found to depend on the synthesis conditions such as Fe/Ba molar ratio, pH of the solution.
An analytic theory for the electromagnetic scattering from a coated perfect electromagnetic conductor (PEMC) sphere is developed. The sphere is characterized by its M parameter, and the coating material by its permittivity and permeability, which may attain arbitrary values, including negative ones. The theory is applied to the calculation of various scattering cross sections. It is found that the scattered fields contain cross polarized components, which do not exist in the case of a coated perfect electric conductor (or perfect magnetic conductor) sphere. Symmetry properties of the solutions, which reflect a generalized form of electric-magnetic duality, are demonstrated.
In this article, designs and analyses of several CCPW (Cylindrical CPW) discontinuities have been realized as microwave reactive elements. The quasi-TEM characteristic parameters of CCPWs have been obtained by CMT (Conformal Mapping Techniques) which provide satisfactory accuracy at microwave frequencies and lead to closed-form analytical solutions suitable for CAD software packages. Then these discontinuities have been simulated in CST Microwave Studio 2006 in order to obtain inductance, capacitance and also input impedance versus frequency and physical dimensions of the elements. The results show that CCPW discontinuities can be used successfully as reactive elements for related applications.
A circulator with a coplanar structure is designed and analysed using a three dimensional finite element method. Based on the proposed design, the circulator is fabricated with a YIG (Yttrium Iron Garnet). The thickness of YIG is only 65 μm. The design is planar and realized by stacking several layers, resulting in a potentially simple and low cost industrial process. Simulated results are better than measured ones but circulation is obtained around 9 GHz. Measured insertion loss is 5 dB and isolation is 36 dB giving interesting perspectives for the device.
A novel wire antenna configuration is proposed to achieve a 90 degree azimuthal beamwidth in the VHF band. The antenna has been manufactured and the measurement results are presented.
PCSS low jitter trigger can reach 65 ps in the condition of high bias electric under the non-liner mode [1-5]; high power transient pulse can be gained by virtue of it. The high power transient pulse in-phase characteristic and other tenets are verified by testing axial electric field strength and axial energy density, which is energy per area at the antenna main radiation direction. In the experiment, axial electric field strength and energy density of antenna array measured in different conditions indicate that axial electric field strength is proportional to the number of antenna elements and the energy density is proportional to the square of the number of radiation units, which means the transient electromagnetic pulses could synthesize in phase perfectly.
A quasi-lumped design of a suspended stripline (SSL) bandpass filter (BPF) exhibiting high signal selectivity is proposed. In the circuit, transmission zeros were implanted to enhance the stopband signal rejection. A sample BPF having an operation band of 6.77--7.33\,GHz was fabricated and measured for performance verification of the proposed design.
Frequency selective surfaces (FSSs) with fractal four legged aperture elements are studied. Three different order fractal elements are discussed for comparison. The results show that by using this novel kind of elements, multiband FSSs with miniaturized elements can be achieved. The ratio of the first resonant wavelength to the periodicity can be up to 10.36. Four passbands for normal incidence or two stable passbands for different incident angle and polarizations can be obtained. The FSS is analyzed by the spectral domain approach.