Recent advances in wireless communications, radar, satellite and space programs have introduced tremendous demands in the antenna technology (Mobashsher et al., 2010; Shakib et al., 2010a; 2010b; Azim et al., 2011; Islam et al., 2009a; 2010b). Among the various type ofantenna, microstrip antennas are of special interest because of their light weight, low profile, compactness and compatibility with integrated circuits, though they suffer from some drawbacks e.g., narrow bandwidth, low gain and excitation of surface waves (Garg et al., 2001; Azim et al., 2010). To overcome these limitations, new methods are still being explored and the interesting features ofElectromagneticBandGap (EBG) materials have attracted the antenna researchers.
for instance, WiMax (wireless interoperatibility for microwave access) for some Asian and European countries operating at 3.3 - 3.7 GHz, WLAN (wireless local area network) IEEE 802.11a operating at 5.15 - 5.85 GHz and X band satellite communication operating at 7.25 GHz - 8.395 GHz. It is thus essential to designanantenna which is not only compact and planar but also has multiband filtering capability to protect the UWB based applications from possible interference from existing narrow band services. While integrating a bandstop filter with UWB antenna may increase the complexity and cost of fabrication , however, antennadesign incorporating band notched characteristics is a simpler way to solve the interference problem.A number of designs have been reported till now for multi band notched functions with in-built structures or design topology to avoid EM interference. Broadly, various techniques ofband rejection capability involves etching slots of various shapes and sizes on radiating patch, microstrip lines or ground plane -, embedding stubs in the radiator patch or in the vicinity of feedline -, use of metamaterial - or electromagneticbandgap structure -. Using these techniques, a number ofantenna designs have been reported in which single band notch - , dual band notch -, triple band notch - and quadruple band notch  have been reported the most. It is observed that in most of the reported designs the antenna size is relatively large and the notched bands are quite wide thereby resulting in reduction in useable bandwidth for UWB communication. Moreover, the mutual coupling among each slot or each parasitic strip leads to a more complicated design procedure requiring tedious simulations and long simulation time to achieve design goals .
Abstract: Microstrip patch antenna has been received tremendous attention since the last two decades and now it becomes a major component in the development of Smart Antenna System for Third- Generation Wireless Network proposed by the ITU-R under the banner of IMT-2000. Smart antenna consists ofan array of antennas associated with it a base-band hardware and control unit (inclusive of the software algorithm) that have the capability to change its radiation pattern according to the direction of the user. This paper describes the design and development of broadband Inverted E-shaped patch microstrip array antennas for 3G wireless network. The antenna was designed for the IMT-2000 operating frequency range of 1.885–2.200GHz and was built as an array of 4x4 inverted E-shaped patches. The beamforming feed network comprises of commercial variable attenuators (KAT1D04SA002), variable phase shifters (KPH35OSC000), and the corporate 16-ways Wilkinson power divider which was developed in-house. The antenna successfully achieves the bandwidth of 16.14% (at VSWR: 1.5) with respect to the center frequency of 2.045 GHz. The antenna is capable of scanning with the maximum scanning angle of ±30º and ±25º in azimuth and elevation respectively.
ABSTRACT: ElectromagneticBand-Gap (EBG) structures are popular and efficient techniques for microwave applications. EBG structures have two main configurations, first EBG substrate and second EBG superstrate. In first case, the patch ofantenna is surrounded with EBG structure that suppress the propagation of surface wave and in second case, layer of EBG structure that call EBG superstrate set above the patch ofantenna to increase the directivity and to reduce the side lobes of the radiation pattern. In this paper, we study the influence of the EBG superstrate on the performances ofan aperture coupled rectangular microstrip patch antenna. The return loss, radiation pattern and directivity are studied using HFSS software. The simulation results show that the gain, directivity and S11 parameter of the antenna with EBG cover are increased at X band (8-12GHz). Compared with the patch feed with the same aperture size but without superstrate, the performance of the proposed antenna is significantly improved.
The design idea was taken from broadband antennas to make the antenna work in a large bandof frequencies of the many broadband antennas [3,8]. Hence the chosen shape of the patch is Sierpienski & Crown Square Fractal Shapes Slotted Microstrip Patch Antenna, with an aim to achieve smaller size antenna. The Sierpienski & Crown Square Fractal Shapes Slotted Microstrip Patch Antenna is presented in fig.1 with front (top) view.
Planar configurations ofmicrostrip technology is placing vital role in the field ofantenna (Sarin et al., 2009). Microstripantenna provides high repeatability of parameters to increase the gain, band width and the size reduction is achieved by using small substrate. Patch can be in any shape like rectangular, circular, square, elliptical sand triangular. Hybrid coupler implementation with Varactor diode and Pin diode is proposed by Sun et al. (2005). Different feeding techniques for UWB antenna are investigated and fabricated (Guo et al., 2002). Figure 1 show the fields associated with anantenna (Yang et al., 2001). Electromagnetic energy coupling in and around patch is done by dielectric material. The electric field is maximum at one end of patch and minimum in other end. This maximum and minimum end will depends the applied signal but electric field at the center of patch is always zero. Electric field in the patch is extended outside patch is causing radiation in a patch and this extended field is known as fringing field (Martin et al., 2007). The proposed antenna is in square array shape with 0.381mm and it resonates at 3.7GHz which includes Wi-Fi and Wi-Max. 1.1. Dual-Fed Circular Polarization Patch Antenna
Abstract— An L-strip proximity coupled circular microstripantenna is proposed. The structure is investigated using circuit theoretic approach and simulated using IE3D simulation software. The patch is designed on a thick substrate of thickness of 11 mm for a design frequency of 3.74 GHz and provides ultra wide band operation. The numerical results for input impedance, VSWR, radiation pattern, efficiency and gain are presented. Bandwidth is found to be dependent on length of horizontal part of L-strip. A bandwidth of 69.52% is achieved (for VSWR≤2) for y 0 =0.112λ 0 and
Nevertheless, the technical hurdles due to the increase in spectrum congestion, interference due to existing systems etc. have to be met in the designing of UWB antennas. Frequency rejection technique is an attractive way to reduce interference between the UWB systems and existing wireless systems without increasing the size or footprint of the antenna . Many kinds of planar UWB antenna designs with notching have been designed and presented -. One of the foremost frequency rejection design technique that meets the need of the current scenario is the incorporation of slots in the antenna patch or in the ground plane so that it does not require any extra space for its implementation ,,,. Slots can be varied in geometry, shape, size and constitution, thus ensuing in the conception of different frequency notch bands. Consequently, several conception strategies for band notching using slots have been embraced making use of various anatomies for slots, such as U-shape , C-shape , annular slots , I-shape , H-shape  and so on. The intended antennadesign incorporates the important essentials for developing an optimum UWB antenna for UWB technology.
In this work, we present a novel simple UWB cylindrical dielectric resonator (CDR) antenna with single band notched characteristics at 3.4 GHz (3.2–3.8 GHz). The rejected frequency was realised by the dielectric resonator and etching a U-shaped slot quarter-wavelength on the circle radiation patch. In this design, tuning of the notched centre frequencies is done by changing the length of the slot and the position of the dielectric resonator. The simulation to optimize design is done using time domain analysis tools from CST Microwave Studio which provides a wide range of time domain signal that are used in UWB system. The numerical analysisof the software tools is based on Finite Difference Time Domain (FDTD). For comparison purpose, HFSS in frequency domain where the numerical analysis is based on Finite Element Method (FEM) is performed. The proposed antenna achieves an impedance bandwidth from 3.3 to over 12 GHz with a return loss< –10 dB and presents the decrement gain and efficiency radiation at approximately 3.4 GHz. The effect of the geometry of the antenna and design principle with frequency band notch characteristics are simulated with the time domain CST microwave simulator (MWS) in Section 2. The radiation pattern and simulation results of return loss with two simulators using CST and HFSS software are presented in Section 3. Concluding remarks are presented in Section 4.
The basis of this antenna structure is a rectangular patch , this incidentally makes the patch covers lower bandof WLAN/WiMAX application. Further to cover both lower and upper band, proposed basic antenna is modified and inverted L- shape strip is joined with rectangular patch(shown in table 2) which results inverted U- shaped radiating. Such a design skill was found to be helpful for improving the antenna’s bandwidth. Anelectromagnetic (EM) solver, Ansoft HFSS, has been employed to analyze the electrical properties and radiation performance of the antenna. The effects of the key structure parameters on the antenna performances are also analyzed and presented in next section.
Abstract: This paper described the analysis and designof a square spiral Microstrip. The spiral is formed by introducing slot in a square patch. This spiral design is introduced to use a single structure for dual band/frequency operations by adding tuning elements. The design parameters for a rectangular patch antenna have been calculated from the transmission line model and using MATLAB. The simulation and modeling of this configuration has been done using Ansoft’s HFSS (High Frequency Structure Simulator) software. The resonant frequency and dimensions are computed from the cavity model for TM 010 mode. The
The conception of dual-band microstrips antennas uses various feeding techniques. However, other configurations, such as aperture, U-shape and shorting pines are also used [1-6]. Techniques used to increase the bandwidth are also valid to reach a functioning in dual-band [1-2]. Thus, for multilayer configurations, the electromagnetic coupling or the coupling by crack, with adjustment of the air gap, can be used to operate the antenna in double band [7-9]. Hybrid configurations by connecting a circular antenna to a waveguide were conceived for a functioning in double band [8-9]. Moreover, novel microstrip antennas are described for this type of functioning [10-12].
In this manuscripts different conventional electromagneticbandgap (EBG) structures are used for the improvement of gain of EBG resonator antennas [9-11]. However, the narrow bandwidth limitation makes the final antenna having small bandwidth. This problem is address by designof PRS having positive reflection phase gradient, which makes these antenna wideband. Therefore a double layer superstrate is proposed whose reflective phase gradient is positive. The design parameters of the proposed EBG structure used for the wideband antenna are depicted in Fig. 1, which contains two dielectric substrates having the same dielectric constant. The dielectric substrates are made of Rogers TMM 10 substrate having dielectric constant value (ε r =9.2), and loss tangent value 0.0022. The
The objective in this section is the designofan infinite Circular EBG slot-patch antenna array. Since the conventional technology presents some limitations such as those in coupling between elements, stability, complexity, the New Multilayered EBG Slot-patch antenna array has the aim to rectify some of these limitations. It is designed to cover high directivity, covering navigation systems, and be substitute for conventional technology antennas. It has been applied with the main challenge here complying with all the specifications given by Wide Area Augmentation System (WAAS). High directivity, stable Axial Ratio and phase center were the most critical parameters. Several EBG technologies have been designed [14,15]. In our case, it is fundamental to analyze a prototype of single circular EBG Slot-patch antenna with periodic lateral walls. Hence, we can obtain an optimization for the infinite array. At the same time antenna dimensions are significantly reduced by the use of high dielectric EBG constant substrates while maintaining high efficiency values. Some precautions regarding the sources placement and coupling should be taken. It is then necessary to check parameter levels all along the antenna operating band: A high coupling level can perturb the global functioning of the antenna array. In our case, this kind of circular multilayered EBG slot-patch antenna with periodic lateral walls is designed and the multilayered technology is checked to give us an idea on the entire attitude of the periodic circular planar EBG slot-patch antenna network. Here, we Keep the same geometric parameters as the previous analysis. Hence, we introduce new change concerning the lateral walls in order to could analyze a whole network composed by infinite patches. That periodic lateral walls condition is very important in
wireless communication known as an electric current method. The writers gave an overview of studies that had been conducted in the undersea communication and detection and through experimental analysis were able to conclude that propagation range in the medium at this frequency can be expanded, only if the current output is increased, without increasing the power output . The experiment was carried out in the Mystic Lakes in Massachusetts, the relative permittivity and conductivity of the lake are 81 and 0.06 S/m respectively. The measured electric field patterns at a distance of 50 m below the surface of the water from the transmitting antenna are quite directional. These were compared with the computed field patterns and their results are similar, with which the conclusion is drawn that traveling wave antenna can be appropriately used for subsurface communication in the lake and also that at 144 MHz bands, and that water behaves like a dielectric medium at this frequency. In , Davis et al presented results of research and experimental validation on SQUIDS antennas operating at ELF bands to demonstrate the feasibility of using the antenna in an underwater environment as well as overcoming the sub-problems associated with its performance. Each of these problems was typically analyzed through measurements and the conclusion as presented by the team shows that SQUIDs antenna is potentially capable to be used as an extremely sensitive ELF RF receiving element on a mobile platform. In addition, the antenna has the ability to operate at a depth of 100 m below the water surface and can also deal with anticipated buoy motions through motion-processing method. In the same year, J. R. Wait presented propagation of ELF electromagnetic waves for Surface ELF Antenna For Addressing REmotely-deployed Receivers (SEAFARER), research in this band had actually been a fertile field of investigation for many years. The project came to address some grays area of Project Sanguine that was fraught with some controversies. In principle the two projects are very alike as the frequency of operation for antennas for this project is the same as that of Project Sanguine. Only that in the latter project power requirements were better estimated, but the US Navy was not able to explain the influence of either project on physical and biological environments. Also, this project has striking similarities and fascinating developments with an early investigation by Nicola Tesla .
The solenoid valve actuation and the pulse control is achieved using an optical crank position sensor circuit. The circuit mainly consists of vital components: optical emitter-receiver (OPB732), Astable multivibrator (LM555)  , TIP 122 Darlington pair  , 200kΩ Trimpot. The working is as explained below:
Abstract — In this paper, a wide stop-bandmicrostrip coupler is presented. The proposed structure consists of coupled lines and step impedance cells, which are integrated to operate at 2.82 GHz for wireless applications. This coupler is formed by a symmetric structure so that the locations of the output ports relative to input are quite similar. Accordingly, the magnitudes (also phases) of S 21
Resonant tunneling diode (RTD) integration with photo detector (PD) from epi-layer design shows great potential for combining terahertz (THz) RTD electronic source with high speed optical modulation. With an optimized layer structure, the RTD-PD presented in the paper shows high stationary responsivity of 5 A/W at 1310 nm wavelength. High power microwave/mm-wave RTD-PD optoelectronic oscillators are proposed. The circuitry employs two RTD-PD devices in parallel. The oscillation frequencies range from 20-44 GHz with maximum attainable power about 1 mW at 34/37/44GHz. Keywords: resonant tunneling diode, photo diode, oscillator, photodetector
Abstract — In this paper, we present a compact and low-profile monopole antenna with a simple structure for the 2.6-2.73 GHz frequency band, the Worldwide Interoperability for Microwave Access (WiMAX) and the Wireless Local Area Network (WLAN) applications. The first configuration of our antenna mainly consists by three radiating elements: inverted L-shaped Stub1, L-shaped Stub2 and a rectangle Stub3. By adjusting the lengths of the three Stubs, three resonant frequencies can be achieved and adjusted separately. Then, the assembled between Stub2 and Stub3 gives the final designof our proposed antenna with a small overall size of 20 mm × 37 mm × 1.56 mm. From the experimental results it is observed that, the antenna prototype has achieved two operating bandwidths (S 11 ≤ -10 dB): the first band from 2.62 to 2.73 GHz (110
The microstrip antennas are used in radar installation, in mobile and satellite communications systems, etc. In the same time the microstrip antennas can be part of the directional or non directional array antennas that use phasing methods; the gain obtained are comparable with gain of parabolic reflector antennas.