A novel complementary split ring resonators (CSRR) is applied to realize a compact Ultra-Wide Band (UWB) bandpass filter based on half-mode substrate integrated waveguide (HMSIW) in this paper. Sharpened rejection skirts and widened upper stopband are achieved due to the two resonant frequencies of the proposed CSRR. Very good agreement is observed between measurement and simulation results.
In this paper, a broadband quadrature hybrid is presented. The hybrid comprises a Wilkinson divider, followed by an improved Schiffman phase shifter. An improved wideband Schiffman phase shifter on a single layer printed circuit board is accompanied by a lumped capacitor between two coupled lines. Lumped capacitor is in parallel with the odd-mode capacitance of the two coupled lines, hence, the odd-mode capacitance is increased and consequently the odd-mode impedance is decreased. Therefore, by this method we can control the ratio of the even mode impedance to the odd mode impedance which is critical in Schiffman phase shifter design. Compared with the cascading Microstrip multi-section coupled lines, our proposed single layer phase shifter is smaller in size. Also, the proposed phase shifter has the greater bandwidth compared to the patterned ground plane Schiffman phase shifter and its realization is simpler because of its single layer structure. As an example, a Schiffman phase shifter at frequency f0 =650 MHz is designed and simulated. With the proposed phase shifter a 90°hybrid is designed, simulated, fabricated and measured. Exprimental results show that the amplitude and phase imbalance between two paths at worth case are within 0.75 dB and 5°, respectively, over the frequency band from 362 MHz to 891 MHz, or around 84% bandwidth. The measured return loss is better than -10.8 dB over the operating frequency band.
With the growth of broadband wireless technology like code division multiple access (CDMA) and ultra-wideband (UWB), lots of development and efforts towards wireless communication system and imaging radar system are well justified. Efforts are also being imparted towards a convergence technology involving both communication and radar technology which will result in intelligent transport system (ITS) and other applications. The authors have tried to converge the communication technologies towards radar and to achieve the interference free and clutter free quality remote images of targets using DS-UWB wireless technology. In this paper, we propose a direct sequence spread spectrum (DSSS) radar for remote sensing in ITS system. We have successfully detected single target using 1D radar imaging, and also separated multiple targets and implemented DSSS radar using software defined radio (SDR) to get continuous connectivity of the system. Authors have sought down the limitations of DSSS radar which according to them can be solved by using adaptive equalizer and rake processing.
The fade margins for 15, 23, 26 and 38 GHz frequency bands are predicted based on one-minute rain rate measurements for four years at Universiti Teknologi Malaysia (UTM) Skudai and the specifications of the given four MINI-LINKS. The availabilities of terrestrial microwave links are also investigated based on rain attenuation data collected from seven operational microwave links at 15 GHz and one at 23 GHz for more than one year. The fade margins for all eight links are measured based on the rain attenuation data collected with different hop lengths. In this paper, the feasibility to design outage-free wireless broadband radio link also highlighted. These results will contribute to the better design of outage-free Broadband Fixed Wireless Access (BFWA) system such as, Local Multipoint Distribution Service (LMDS) and IEEE802.16 in tropical regions.
In this paper, a novel architecture of using cascaded Butler Matrices (BM) integrated with Low Noise Amplifiers (LNAs) is proposed. By using the narrow beams available from the Butler Matrix, it is possible for a receiver to increase the gain in the desired signal directions and reduce the gain in interference directions. Hence, high-gain narrowbeam signals for long-range application are produced. A novel technique is introduced which uses high linearity LNAs and a second Butler Matrix, acting as a mirror of the first Butler Matrix, reconstructing the antenna patterns of the individual radiating elements. The resulting outputs have high linearity and broad beam width that can be used for short-range communication. Design of the Butler Matrix, Low Noise Amplifier, Wilkinson Power Divider and High Linearity Low Noise Amplifier are presented in this paper. A final design of active antenna beamforming network using cascaded Butler Matrices integrated with LNAs is proposed. The beamforming network provides a method, which could be applicable in vehicle communication systems, where long-range communications with roadside beacons and short-range communications with the fast moving vehicle are both required.
In this paper, we present a distributed particle filter (DPF) for target tracking in a sensor network. The proposed DPF consists of two major steps. First, particle compression based on support vector machine is performed to reduce the cost of transmission among sensors. Second, each sensor fuses the compressed information from its neighboring nodes with use of consensus or gossip algorithm to estimate the target track. Computer simulations are included to verify the effectiveness of the proposed approach.
This paper investigates the properties of probe fed cavity-backed fractal aperture antennas. The problem is formulated using the finite element-boundary integral (FE-BI) method in which the field inside the cavity is formulated using the finite element method, and the mesh is truncated at cavity aperture surface using the boundary integral method. Several dual-band cavity-backed fractal aperture antennas based on Sierpinski gasket, Sierpinski carpet, plus shape fractal and Minkowski fractal are investigated. The numerical results obtained from the FE-BI code have been validated with simulations on HFSS.
A planar dual-band semicircle shaped antenna for multi-input multi-output (MIMO) systems is introduced. The antenna was studied experimentally regarding bandwidth and radiation patterns. The measured -10 dB return loss bandwidth is from 2.27 to 2.53 GHz and 5.03 to 5.58 GHz, covering all the 2.4/5.2 GHz WLAN bands. Details of the antenna design, simulated and measured results on the return loss and the E- and H-plane radiation patterns of the proposed antenna are presented. The multi-feed 4-elements planar array is simulated using the commercially available software Ansoft HFSS and fabricated that are verified by good agreement between simulated and measured results. The enhanced performance is obtained by placing antennas uniquely to suppress mutual coupling and utilizing supplemental structure to miniaturize the size of the antennas.
In this paper CSRRs (complementary split-ring resonators) are used to suppress the first spurious response in microstrip hairpin filters. The CSRRs are merged in the filter structure, and therefore the filter size is not increased. The design methodology is presented, and a filter with center frequency at 3 GHz is designed, fabricated and tested as an example. The characterization of this new filter shows the efficiency of the proposed approach to improve filter response with spurious rejection up to 20dB while the size is even slightly reduced.
Use of water with different molecular mobilities could affect drug dissolution of a dosage form and such profile of water might be modifiable using microwave. This study investigated the effects of microwave on water and its influences on dissolution of free drugs and drugs in calcium-crosslinked alginate beads using sulphanilamide and sulphamerazine as hydrophilic and hydrophobic model drugs respectively. The water was treated by microwave at 300 W or without pre-treatment. The drug dissolution, pH and molecule mobility profiles of untreated and microwave-treated water were examined. Microwave-treated water had higher pH and water molecule mobility. The latter was characterized by higher conductivity, lower molecular interaction and crystallinity profiles. The dissolution of hydrophilic and hydrophobic free or encapsulated drugs was enhanced using microwave-treated water due to its higher molecular mobility. The untreated water of the same pH as microwave-treated water did not enhance drug dissolution. The drug dissolution from beads was increased by higher water uptake leading to matrix erosion and pore formation using microwave-treated water and was not promoted by the formation of non-crosslinked hydrated alginic acid matrix in untreated water of lower pH. Microwave treatment of water increased water molecule mobility and can promote drug dissolution.
A down-link CATV/fiber-to-the-home (FTTH) and up-link FTTH transport system employing a reflective semiconductor optical amplifier (RSOA) as wavelength reuse and remodulation schemes is proposed and experimentally demonstrated. By using -1 side mode injection-locked/optoelectronic feedback techniques, brilliant performances of carrier-to-noise ratio (CNR), composite second-order (CSO), composite triple beat (CTB), and bit error rate (BER) were obtained for down-link transmission; low BER value was also achieved for up-link transmission over a 50-km single-mode fiber (SMF) transmission. Such a CATV/FTTH transport system is suitable for broadband access fiber networks.
This paper presents comprehensive methods for the design of a 900-MHz CMOS transmit/receive (T/R) switch with high power-handling capability. Techniques such as RF floated body to extend the bandwidth and decrease the insertion loss, and stacking architecture with high substrate isolation to enhance the power-handling capability are used for the design of a T/R switch on a standard 0.18um triple-well CMOS process. The measured performance of the T/R switch demonstrates the effectiveness of the methods presented in this paper such that insertion loss less than 1.0 dB, isolation up to 35.2 dB, and input 1-dB compression point of 30-dBm can be achieved at 900-MHz.
In this paper, a novel electromagnetic bandgap structure (EBGs) is proposed, which is similar to the mushroom-like EBG. By introducing double reverse split rings (RSR) into the square patch, the size of EBG cell is reduced by 30%, and the bandgap achieves bandwidth about 65%. A fractal microstrip antenna is implemented using the EBGs as a ground plane, and the measured results show that the reduction in the surface wave level is remarkable. Compared with the reference antenna at 5 GHz, an approximately 8 dB improvement of the return loss is achieved, and the back lobe is reduced by 10 dB in E plane and 8.73 dB in H plane at the resonant frequency, respectively. The front-back ratios of the antenna have significantly increased from 4.9 GHz to 5.2 GHz.
This paper presents the design of a compact rectangular dielectric resonator antenna (RDRA) for wireless applications. A metal plate has been attached to top surface of the RDRA to achieve significant reduction in the resonant frequency of the antenna. A simple microstrip feeding mechanism has been used to excite this compact rectangular DRA. Performance parameters such as resonant frequency, impedance bandwidth, and volume of this compact RDRA are compared with those of the conventional RDRA. Measured characteristics of these RDRAs are in good agreement with the simulated results. The size of the compact RDRA using a low dielectric constant (εr = 10.3) material resonant at 2.4 GHz is 30 mm × 10 mm × 6.3 mm with a ground plane size of 200 mm × 200 mm.
A new method for evaluating the performance of the shield and coupling through holes on braided shields is introduced. The method is based on conducted immunity test. A comparison is made between two kinds of shields, based on introduced technique. One is braided shields and the other is adhesive foil that does not contain any holes. The value of coupling through holes in braided shields is determined via a new technique.
In this paper, a direct three dimensional Finite-Difference Time-Domain (3D-FDTD) approach is implemented to investigate the electromagnetic behavior of a Half Hollow Cylindrical Antenna. The conformal shape of this antenna is studied using the Conformal Finite-Difference Time-Domain (CFDTD). We shall prove that a variation of the antenna shape generates an important shift of the values of the resonant frequency (about 0.467 GHz). Compared with the planar shape, the geometrical shape reduces the space occupied by the antenna of about 36,28%.
A novel microstrip fed ultra-wideband (UWB) antenna with different band rejection techniques is presented in this paper. The antenna consists of a maple-leaf shaped radiator fed by a microstrip line with a finite ground plane on the other side of the substrate. The size of the UWB antenna is 30.5 × 35.5 mm2 which is only about 0.3 × 0.35 λ2 at 3 GHz. The calculated impedance bandwidth of the proposed antenna ranges from 3 GHz to 14 GHz with relatively stable radiation patterns. Two different techniques have been implemented to achieve band-notch characteristic in the 5.0-6.0 GHz WLAN frequency band. The first one uses an H-shaped slot cut away from the radiating patch while the other one uses two rectangular slits in the ground plane creating defected ground structure (DGS).
In this paper, we propose a novel genetic algorithm (GA) called immunity GA (IGA) for array pattern synthesis with interference suppression using digital amplitude only control. The IGA is based on crossover evolution where the crossover operator is a variant of the known GA operator. A new formulation of the array factor transform for a specific number of elements N is expressed by a discrete cosine transform (DCT) with pre-computed DCT matrix. Evaluating thousands of candidate solutions generated by the IGA using the precomputed DCT matrix will result in a high speed computation. This high performance allows us to find a good approximation of the absolute minimum SLL of synthesized arrays with digital amplitude control. Simulation results show the effectiveness of this new algorithm for pattern synthesis with low SLL and null steering.
This paper reports the design and development of rectangular microstrip antenna comprising a novel slot for enhancing the impedance bandwidth and gain. By incorporating a slot of optimum geometry at suitable location on the radiating patch, the antenna provides 78.08% (3.39 - 7.73 GHz) of impedance bandwidth and 3dB of gain without changing the nature of broadside radiation characteristics when compared to conventional rectangular microstrip antenna. The proposed antenna may find applications in mobile WiMax, IEEE802.11a, HIPERLAN/2, cordless phones, fixed wireless etc. Design concept of antennas is given, and experimental results are discussed.
A compact planar ultra-wideband (UWB) dipole antenna having band-notched characteristic is presented. The dipole antenna has the shape of a modified annular ring and is fed by a 50-Ω microstrip line. Cutting a slot in each radiating annular ring improves the input impedance bandwidth. With the design, the return loss is lower than -10 dB in 3.1 GHz-10.6 GHz frequency range. In addition, band-notched filtering properties in the 5.15 GHz-5.825 GHz are achieved by etching four rectangular slits in the ground plane, and the radiation pattern is similar to a conventional dipole antenna. A good agreement is found between the simulation and the experiment. Details of the proposed antenna design and the experimental results are presented.