Abstract—This article presents the design, simulation and testing of an Ultra Wide Band (UWB) planar monopoleantenna with WLAN band-notch characteristic. The proposed antenna consists, the combination of planar monopoleantenna with partial ground and a pair ofAMC structures. The AMCstructure used for the design is mushroom-like. Design equation of EBG parameters is also proposed for FR4 substrate using transmission line model. Using proposed equations, Mushroom-like EBG structure is integrated along the feed line of a monopoleantenna for WLAN (5 GHz – 6 GHz) band rejection. The Current distribution and equivalent circuit model ofantenna is used to explain band-notch characteristic of EBG resonator. The proposed antenna is fabricated on an FR4 substrate with a thickness of 1.6 mm and ε r = 4.4. The measured VSWR characteristic is less than 2 for complete UWBband except for WLAN
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 design an antenna 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 UWBantenna may increase the complexity and cost of fabrication , however, antenna design 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 electromagnetic band gap structure -. Using these techniques, a number ofantenna designs have been reported in which single bandnotch - , dual bandnotch -, triple bandnotch - and quadruple bandnotch  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 — In this manuscript, a novel hybrid dielectric resonator antenna for ultra wideband (UWB) applications is designed, and single band notched performance is proposed. The circle radiating patch is printed on the FR4 substrate of 1.64 mm thickness and loss tangent tan =0.02, and is fed by the coplanar waveguide. The size of the UWBantenna was minimised to 50 –40 mm 2 . The cylindrical dielectric resonator (CDR) was used to broaden the bandwidth and achieve an impedance bandwidth of more than 113%, covering a frequency range of 3.3 to more than 12GHz. WIMAX band notched characteristics of the antenna to reject (3.2 –3.8GHz) were realised by etching a U-shaped slot in the radiating patch. The centre notch frequency can be adjusted from 3.4 to 4.5 GHz by changing the position of the CDR. The band notched characteristics, VSWR, and radiation patterns were studied using the CST microwave simulator and confirmed with the frequency domain ANSOFT high frequency structure simulator (HFSS).
annular ring patch having inner and outer radii ‘a’ and ‘b’ respectively. In this analysis, for some calculation purpose, it is assumed that annular ring patch with inner ‘a’ and outer radii ‘b’ is equivalent to square ring patch with inner width ‘2a’ and outer width ‘2b’ (Fig. 1). It is because many characteristics of square ring patch are similar to annular ring patch [13-14]. Annular ring patch antenna is parallel LCR resonator for one resonant mode and the equivalent circuit can be given as shown in Fig. 2a.
The backfire antenna is created by H. W. Ehrenspeck and his associates at the Air Force Cambridge Research Center, Bedford, Mass. in 1959 -. It was obtained by placing of a big reflector at the open end of an end-fire antenna perpendicularly to its axis. Thus, the antenna increases its length for the surface wave which leads to the improvement of the antenna gain and directivity. The geometry of the backfire antenna is shown in Fig. 1. It consists of a source F (for example, a dipole or crossed dipole), a surface-wave structure S (dipole array, corrugated rod, dielectric rod or dielectric-covered metal rod) and two parallel disk reflectors: small reflector R 1 and big reflector R 2 .
prototype has been produced by connecting triangular, quadrangular and rectangular pieces of the dielectric substrate. We have performed numerical sweeps of the crossed dipole dimensions, since the subreflector is neither plane nor an infinity array, as considered in the Floquet method. The numerical sweep analysis has been conducted to guarantee high reflectivity response in the X-band for increasing the antenna gain. Fig. 2(a) shows the unit cell from the Floquet Method, whereas Fig. 2(b) displays the FSS-based subreflector details, including its final dimensions.
In UWB localization systems, distance to the target is obtained from time-of-arrival (ToA) of sub-nanosecond trans- mitted pulses. These systems typically achieve centimeter resolution . Regulations for UWB authorize unlicensed use of 3.1 to 10.6 GHz spectrum in US  and 6 to 8.5 GHz in Europe , subject to a spectral power density limit of dBm/MHz. This ensures spectrum sharing with other estab- lished narrowband applications without mutual interference, but at the same time it implies a severe range limitation. UWB systems are highly immune to multipath interference, have low power consumption and involve low complexity transceivers since baseband transmission is used. Commercial UWB lo- calization solutions already exist based upon active tags , . However, passive UWB tag solutions would be more at- tractive for low-cost, maintenance-free large-scale deployment applications, if the range limitation could be overcome. In fact, regulation compliant ultra-wideband pulses are insufficient to energize passive tag’s chips, unlike what is done in UHF RFID. An alternative approach has been presented in  where a narrowband continuous wave UHF RFID signal is broadcast by the reader, which carries the clock, commands, and energy to power-up the chip on the tag, whereas it responds with UWB pulses. The feasibility of the UHF/UWB hybrid concept is demonstrated in  using a breadboard circuit with discrete components and well separated UWB and UHF antennas to
The frequency divider plays an important role in the high speed circuit. It is a crucial building block for generating different carrier tones from a single reference frequency of the VCO. The sinusoidal signal can not be divided down into other frequencies since it only contains one frequency component. In order to perform frequency division, the sinusoidal signal must be converted to digital square wave first. Then, after division at digital domain, the signal is low-pass filtered to obtain the desired sinusoidal waveform. There are three types of frequency dividers: (1) flip-flop based frequency divider, (2) injection-locked frequency divider (ILFD), and (3) regenerative frequency divider. The ILFD uses a VCO and the frequency is locked to a harmonic of the input frequency. The drawback of ILFD is it exhibits a very narrow frequency lock range. A regenerative frequency divider consists of a mixer and a low-pass filter in a closed loop feedback form. The regenerative divider performs a wider frequency range, but it must use a number of passive components which occupy a large chip area.
Lastly, the results obtain from both simulation and experiment shows that most of the value attained were not exactly similar. This is due to the fact that most equipment has their setting errors. Also, the condition of surrounding must be considered. Not to forget human error such as soldering and during fabrication. Furthermore, the frequency was shifted from the 10 GHz to 9.84 GHz. It may be due to the grounding effects.
The antenna geometry is shown in figure 1. All the dimensions are in mm. First a square microstrip patch antenna is designed based on standard design procedure to determine the length (L) and width (W) for resonant frequency. For this the ground plane is kept finite and is of the size 50 mm x 50 mm. The size of the square patch is 45 mm x 45 mm. Inside this square patch two rectangular slots of size 30 mm x 10 mm and centered at (22.5 mm, 22.5 mm) of the square patch are cut. Each arm of the above slots is extended at right angles with size 10 mm x 5 mm and hence resulting into a typical Swastika symbol slot. In between the patch and ground plane there is a substrate called glass epoxy whose dielectric constant is 4.2 and the height of which 1.6 mm.
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 of Electromagnetic Band Gap (EBG) materials have attracted the antenna researchers.
kallidin . The latter lacks an acidic N-terminal amino acid, and is converted to bradykinin only in the absence of calcium. Together these results support the idea that mammalian APA is important for regulation of brain function, and blood pressure in particular, but further substrates may yet be found. Some studies suggest a role for APA in blood vessel formation, and these could reflect a more general effect of APA on angiogenic mechanisms such as a role in degrading the extracellular matrix . Ogawa et al.  have shown that exosome-like vesicles isolated from G. b. brevicaudus venom contain APA and, like mammalian APA, degrade both angiotensin II and CCK-8. It is therefore possible that a role of snake venom aminopeptidases is to cleave the N- termini of such oligopeptides in the victim and thus affect the corresponding physiological processes. Alternatively the amino- peptidases may simply assist the general degradation of the host tissue , perhaps increasing its permeability to other venom components . A further possible role for snake venom aminopeptidases could be to process other toxins within the venom  and it is entirely possible that the enzymes have more than one of these suggested roles. The diversity and relatively high levels of aminopeptidase in snake venoms offer a valuable source of protein for characterisation of this complex family of enzymes. As this is an important group of venom enzymes which may be involved in critical envenomation effects in victims of snake bite, these enzymes could be potential therapeutic targets for develop- ing novel snake bite treatments. This study clearly points towards the importance of complete analysis of individual components of snake venom in order to develop effective therapies for snake bites.
Abstract: Problem statement: In this study Microelectrical Mechanical System (MEMS) switches were proposed to design a reconfigurable/multi-bandantenna to replaced PIN diode switches or semiconductor switches due to lower insertion losses, good isolation, much lower intermodulation distortion, and lower power consumption. The antenna is able to operate at very high frequencies. Approach: A reconfigurable antenna that is capable to operate at several frequencies was proposed by introducing two adjacent patches along with main radiating patch and two MEMS switches. Parametric analysis of the size of the wing patches was done for finding optimum size. A comparative study was done for Alumina, SiN, GaAs and Teflon as MEMS bridge materials for finding better results in terms of return loss and number of bands. The design was performed by using 3D electromagnetic simulator HFSS considering ideal MEMS switches. Results: It was found that SiN as MEMS bridge material makes the antenna to operate at 16.76, 23.56 and 27.7 GHz in the “OFF” states and operate at 20.9 and 21.91 GHz in the “ON” states of MEMS switches. Conclusion/Recommendations: MEMS cantilever beam material played an important role for providing antenna to operate at multi-band frequencies. The proposed multiband/reconfigurable antenna can be implemented with easy fabrication process steps by the Sandwich method of fabrication.
In this work a double side patch dipole antenna fabricated on both side low loss substrate as shown in the Fig. 4. Fig. 4 (a) shows the top view and one pole of each dipole can be seen. The other pole of each dipole element is etched on the bottom of the dielectric substrate as shown in Fig. 4 (b). The antenna is design on a low loss dielectric substrate with a thickness of 0.8mm and having dielectric constant of 2.65 . The dipole patch antenna is spaced from the ground plane by 2.5mm air gap with Teflon spacers at all corners of the substrate. These dielectric spacers are also included in the design ofantenna in the CST. The air gap drastically reduces the surface wave and thus gives us good impedance matching at the desired frequency bands. The dimensions of the ground plane is 2.4 λ 0 x
In this paper, we propose a triangular-slot antenna combined with rectangular patch as the tuning stub to produce a dual bandantenna operating at 2.3/3.3 GHz bands that can support both nomadic and mobile WiMax applications. The proposed antenna uses DICLAD material substrate that can provide larger gain compared to that of FR4 material due to lower value of relative permittivity (relative permittivity of DICLAD 527 is 2.5 compared to 4.4 of FR4). However, the use of low cost material FR4 is more attractive, but should be using a more complex array design to compensate for the antenna gain.
Multipath and high temporal and spatial variability of the propagation environment causes severe signal degradation in shallow water acoustic digital communications. Among the many solutions that have been proposed most known is adaptive equalisation where cyclic training signals are used to adapt the equaliser to the variability of the acoustic channel. When the channel is rapidly changing, equaliser coefficients are frequently adapting and effective transmitting rate rapidly decreases. Another approach consists in using a priori information obtained from acoustic propagation models. These models can give a deterministic estimate of the true channel impulse response that can be used to detect the transmitted signals. In practice, the use of deterministic acoustic models is mainly dependent of the accuracy of the input environmental parameters. As a first step, this paper presents an exhaustive study of the signal detection sensitivity to model parameters mismatch. The scenario used is composed of a 100m depth water column with range dependent characteristics. The water column is located over a 10m thick sediment layer with variable properties. Source-receiver communication is made over a variable distance between 500 and 600m with the source near the bottom and the receiver near the surface. The communication signals are narrow band (1.5KHz) pulse amplitude modulated with a carrier frequency of 15KHz, and the detector is based on the Maximum-Likelihood Sequence Detector (MLSD).
Abstract — This work presents a new Ultra Wide Band (UWB) beamforming fifth-order derivative Gaussian pulse transmitter with dual small Vivaldi antennas for remote acquisition of vital signals in impulse radar applications. The system consists of a programmable delay circuit (PDC or τ), a UWB pulse generator (PG) circuit and an array of two Vivaldi planar antennas. The circuits is designed using the 0.18μm CMOS IBM process. Spice simulations show the pulse generation with 90mVpp amplitude and 300ps width. The average power consumption is 120µW per pulse, using a 2V power supply at a pulse repetition rate (PRR) of 100MHz. Full tridimensional electromagnetic simulations, using CST MWS, show the main lobe radiation with a gain of 5.5dB, and a beam steering between 20º and -17.5º for azimuthal (θ) angles at the center frequency of 7.5GHz.
a series feed array with a usable frequency range of 75 − 79 GHz. This approach allows one to neglect the effects of the radiation caused by the delay lines which impedes the usage of determin- istic design methods. By using a PSO their radiation effects are automatically considered as the objective function is based on the radiation pattern. The design process of a differential feeding network in substrate integrated waveguide (SIW) to avoid stray radiation is also shown. Typical microstrip feeding networks can impair the sidelobe level of the isolated antenna due to higher or- der modes and surface wave radiation, but it is proven in this chapter that by using SIW instead the effects of the feeding network can be neglected. The final result is an antenna that can be operated in its full frequency range without significant changes in the radiation pattern, no beam squint, re- duced sidelobe level and reflection coefficient magnitude smaller than −12 dB. Table 5.1 provides a comparison between the work of this chapter and the state-of-the-art, showing that in fact our antenna is able to provide a much wider operating frequency span when compared with current designs. In some works of the state-of-the-art it was impossible to evaluate beam squint as the authors provide the radiation pattern for the centre frequency only due to the inherent narrowband behaviour of their antennas.
Integrated antennas are a combination of solid-state devices and circuits with printed antenna structures and comprise of integrated radio system elements that are fabricated using inexpensive printed circuit techniques  . The area of integrated antennas has become an important area of research because it can give excellent results in term of efficiency, compactness, lightweight and low cost compared to the conventional systems. The main disadvantage of microstrip antenna is an intrinsic limitation in bandwidth, which is due to the resonant nature of the patch structure [2 ]. This problem gives a new motivation for research on solutions to overcome the bandwidth limitations of the microstrip antenna. Therefore, for applications that need to increase the bandwidth for operating at two separate sub-bands is represented by dual-frequency microstrip antenna [3,4] . This antenna can be more useful for system that can receive and transmit at the same time.
Electrical smart antenna systems work in the following way: After the digital signal processor receives signals collected from each antenna element, it computes the direction-of- arrival (DOA) of the signal of interest (SOI). It then uses adaptive beamforming algorithms to produce a radiation pat- tern that focuses on the SOI, while tuning out any signal not of interest (SNOI). Figure 1 shows the functional block dia- gram of a smart antenna system.