Search

A compact sinusoidal tapered slot Vivaldi antenna is designed for X and Ku band applications. The bandwidth of the antenna is improved with two circular stubs before the tapering. A rectangular slot is included before the two stubs to reduce the aperture width of the antenna. The feed line is then terminated with sectorial stub to have better coupling to the slot. The profile of the tapering of slot is designed as sinusoidal variation to have good end fire radiation for the entire frequency range. The simulated single antenna has return loss less than -10 dB in between the frequencies 8.2-20 GHz. A five-element linear array is designed, simulated and prototype model is fabricated. The simulated and experimental results show return loss is less than -7.5 dB for the frequency range of 8.1-20 GHz. The maximum gain of single element and array is 4.6 dBi & 7 dBi respectively. The Co and cross polarization radiation patterns are measured. The designed Vivaldi antenna array is used in electronic warfare and phased array applications.

In this paper, a novel compact broadband antenna at UHF frequencies is presented with canonical shapes. Hemispherical, conical and cylindrical shapes have all been considered for antenna configuration. The designed antenna provides an instantaneous frequency range from 370 to 5,000 MHz with omnidirectional characteristics. The antenna was simulated in CST Microwave Studio, fabricated and evaluated; the results are presented. The simulated and measurement results are in good agreement. The antenna has voltage standing wave ratio (VSWR) ≤ 1.9:1 in 400–570 MHz, 2,530–3,740 MHz and 4,180–4,620 MHz; it has VSWR ≤ 3:1 over the operating frequency range 370–5,000 MHz and the measured gain varies from -0.6 to 4.5 dBi over the frequency band. The concept of canonical-shaped antenna elements and the incorporation of triple sleeves resulted in a reduction of the length of the antenna by 62% compared to the length of a half-wave dipole antenna designed at the lowest frequency. The antenna can be used for trans-receiving applications in wireless communication.

A novel miniaturized dipole antenna design incorporating triple sleeves and shorting load leading to enhanced bandwidth is proposed in the present work. The Triple Sleeve Dipole Antenna with Shorti...

In this study, a novel metamaterial inspired compact cylindrical conformal dual-band antenna with a shunt fractal inductor and bottom patch is proposed. The conformal antenna consists of three meander lines type unit cells of composite right/left-handed metamaterials for modification and compactness. To improve the operating bandwidth in the first band i.e at 2.45 GHz, a shunt fractal inductor with large inductance is proposed. A similar patch with a slot along the bottom side is additionally used for better impedance matching. The second band at 3.5 GHz is obtained due to the loading of two meander line unit cells on the patch as parasitic elements. The proposed conformal antenna is placed on a 15 mm radius cylinder whose equivalent planar dimension is 0.48 λ g × 0.36 λ g (where λ g is the guided wavelength). Asymmetrical coplanar waveguide feed is implemented. Measurement results showed that the proposed cylindrical conformal antenna achieves a wideband −10 dB fractional bandwidth of 44.5% and a gain of 1.26 dBi at the operating frequency of 2.45 GHz and 4.5% of bandwidth and a gain of 2.2 dBi at the 3.5 GHz. The radiation efficiency is 70 and 86% at the said frequencies respectively. There is good agreement between measured and simulation data.

In this paper, novel techniques are presented for gain enhancement of a wideband directional conformal antenna. Initially a wideband conformal antenna is proposed as a basic antenna which consists of an array of three fork shaped elements. To achieve the gain enhancement of the basic conformal antenna, three triangular shaped parasitic elements and an array of 3 × 6 number of low index metamaterial unit cells are integrated on both side of the substrate. The phase velocity in the metamaterial region is higher than the other region due to low refractive index as compared with other region. So, the proposed metamaterial can be considered as a beam focusing lens. As a result, the proposed antenna is more directive with narrow beamwidth and the half power beamwidth is reduced by 24° in the H-plane. The gain of the proposed conformal antenna which is integrated with parasitic elements and metamaterial unit cells is enhanced by 1.8 dBi compared to basic conformal antenna. The impedance bandwidth of the proposed conformal antenna achieves a bandwidth of 22.3% from 3.1 to 3.88 GHz which is suitable for WiMAX application.

In this article, a novel wideband cylindrical conformal antenna using a wide slot in the ground plane is proposed. A bow-tie-shaped patch antenna is designed for Global Positioning System applications. The bandwidth of the antenna is improved by using a similar bow-tie-shaped slot in the ground plane with a larger dimension. The bandwidth is further enhanced by introducing a dumbbell-shaped slit in the patch. The antenna is fed by a 50- Ω " role="presentation"> Ω Ω \Omega microstrip line. The proposed planar antenna is printed on a ground plane of size 0.5 λ " role="presentation"> λ λ \lambda mm × " role="presentation"> × × \times 0.5 λ " role="presentation"> λ λ \lambda mm, where λ " role="presentation"> λ λ \lambda is the operating wavelength, and then it is transformed into a cylindrical conformal antenna with the desired radius of curvature. The proposed planar antenna is simulated, fabricated, and measured for conformal geometry with good agreement between measurements and simulation results. It is observed that the conformal antenna exhibits a fractional bandwidth of 81.4 % " role="presentation"> % % \% operating from 0.75 to 1.78 GHz, which is useful for all GPS and Galileo frequencies. The radiation pattern exhibits an omnidirectional pattern and gain of the proposed antenna is 3.5 to 4.78 dBi within the operating frequency range.

In this paper, a novel technique using frequency selective surface (FSS) superstrate is proposed to increase the antenna gain. In addition to that, a combination of reactive impedance surfaces (RIS) is included to enhance the bandwidth. So, a conventional pentagon shape patch antenna is designed at 5.3 GHz. The frequency selective surface is designed as a 6×6 array of unit cell structures to operate around 5.3 GHz. Each unit cell consists of three metal conductive layers with substrates in between them. Reactive Impedance Surface is considered as an array size of 6×6 square patches embedded between two substrates. FSS is designed on Rogers 4003C and FR4 is used for RIS. The pentagon shape patch antenna is designed on RIS. A cavity created by the contribution of these layers acts like a fabry perot resonator which improves the gain and bandwidth simultaneously. The proposed antenna has an impedance bandwidth of 17.72% (4.93-5.89 GHz); this is about a 10 percent improvement over the impedance bandwidth of a conventional pentagon shape antenna and the axial ratio bandwidth is 2.4% (5.01-5.14 GHz). The designed antenna gain is around 12dBi; this is about a 9 dBi improvement over the gain of a conventional pentagon shape antenna.

In the proposed paper, design of an omnidirectional antenna using directional antennas is proposed at L2 band(1.2268 GHz.) for GPS applications. The Omnidirectional pattern is obtained using directional antennas by arranging them in such a way that their far field patterns interfere constructively and create an Omnidirectional pattern. To validate our design proposal Omnidirectional antenna is designed using directional antennas in simulation tool. The simulated results are observed, which illustrates good performance of proposed antenna. Bandwidth obtained for designed antenna is 45.4 MHz

A novel compact broadband Canonical Sleeve Antenna (CSA) covering 500-3600 MHz with omni directional characteristics is presented in this paper. A new method is employed in which the radiating antenna structure is designed as combination of three different canonical structures: hemispherical, conical and cylindrical elements. To accomplish the broad bandwidth with compact size, dipole antenna is designed by using cylindrical sleeve over the hemispherical dipole with conical extensions and cylindrical attachments. Performance characteristics of CSA is simulated and compared with BiConical Antenna (BCA) and other antenna configurations and found to be best antenna configuration with compact form factor. The antenna has height of 111.43 mm and diameter of 116.66 mm. Simulation studies are carried out using CST Microwave Studio. The simulated results are validated by fabricating CSA and evaluating its performance metrics. CSA has 7.2:1 bandwidth with measured VSWR

A broadband gradient refractive index (GRIN) metamaterial is used to improve the gain of the tapered slot antenna. The proposed metamaterial is capable of reducing the side lobe level of the antenna. The gradient refractive index (GRIN) metamaterial is constructed by using non-resonant parallel-line unit cells with different refractive index. Due to the non-resonant structure, the proposed unit cell exhibits low loss and large frequency bandwidth. The metamaterial, whose effective refractive index is lower than that of the substrate on which the antenna is printed. Therefore, the proposed metamaterial is act as a regular lens in beam focusing. The GRIN metamaterial is integrated in front of the antenna which has the capability to manipulate electromagnetic wave accurately. The measurement results indicate that the reflection coefficient of the antenna is below -10 dB over the frequency band from 3 to 11 GHz. The radiation pattern of the antenna shows the beam width becomes narrow and directive with low side lobe level. The peak gain is increased by 2.1 dB at 9.5 GHz.

This paper introduces a novel technique to enhance the gain of the basic monopole antenna by using broadband gradient refractive index (GRIN) metamaterial. The proposed GRIN is designed by using a parallel-line unit cell metamaterial with different refractive index. A seven GRIN lens is placed on the omnidirectional printed basic monopole antenna, perpendicularly. Due to the non-resonant and subwavelength properties of the parallel-line elements, the proposed GRIN metamaterial lens has a broad bandwidth property with low loss. The simulation and measurement results confirmed that the beam is more directive with narrow beam width. The measured reflection coefficient of the GRIN antenna is below -10 dB over the frequency bandwidth of 3.4-11 GHz. Due to GRIN lens, the peak gain of the basic monopole antenna is increased by 5.3 dB at 8.8 GHz.

A novel wideband log spiral antenna with superstrate design is proposed for C-band applications. Initially spiral antenna is designed on a 20.4 mm diameter then Minkowski fractals are placed on outer boundary of spiral antenna. The bandwidth of an antenna is improved using Minkowski fractals. Further one more single layer is added as a superstrate design which making the radiation pattern unidirectional. The single layer spiral antenna with fractals has return loss bandwidth of 0.59 GHz and fractional bandwidth of 11.98% where as double layered spiral antenna has return loss bandwidth of 1.34 GHz and a fractional bandwidth of 27.50%. The proposed antennas have a gain varying in the range of 2.5 to 4.64 dBi over the operating frequency band for both the single layer spiral antenna and double layer (superstrate) spiral antenna.

In this paper, a compact log spiral antenna with slots on the spiral arm is designed to achieve wideband bandwidth and compact structure. These circular slots are also providing better impedance matching in terms of lower return loss. The introduction of slots increased the gain of the antenna. The proposed antenna has achieved a fractional bandwidth of 43.83 % over the S-band frequency range from 2.68 to 4 GHz. The radiation pattern is bidirectional along broadside direction. The gain of proposed antenna varies from 2.2 to 3.4 dBi over the S-band frequency range.

This paper proposes the design analysis and implementation of single element, two element and four linearly placed elements implanted on wearable substrate. Effect of FR4 and Jeans wearable substrates are studied with the designed models. The traditional square shaped basic patch antenna is fixed with the dimensions of 20×20 mm2, The base antenna is transformed to two element model assuming both the elements to be similar with the inter element spacing of 34mm. Finally the structure is analyzed for 4×1 linear shaped array. Illustrative comparisons of all three models with both the substrates are evaluated in this work. The overall size of the linear antenna array with inter element spacing is very small compared to the wavelength at the resonant frequency. The structures with the line feeding technique are performed in terms of return loss bandwidth (S 11 ), gain and antenna efficiency using the CST software simulator. Significance of the proposed linear antenna array with Jeans cloth (1.7) is compared with the FR4 (4.4). Novelty of this work lies in performance of wearable antenna array which resonates at frequency of 5.3GHz WLAN application with the high gain value of 13.09dBi.

In the present paper a novel technique is applied to ground plane of patch antenna to reduce the size of the radiating patch and simultaneously increase the gain of the antenna. A rectangular microstrip antenna is designed for Wi-Fi application at 2.45 GHz. Fractal structures are self symmetry structures which can be used for size miniaturization. Sierpinski carpet fractal slots are applied to the ground plane of the rectangular patch antenna working at 2.4 GHz frequency. The results are simulated for first iteration and second iterations of fractal DGS antenna. There is size reduction of the radiating patch is 30.78%, 32.9% for 1st and 2nd iterations fractal slots respectively. The performance of the antenna has also showed improvement.

A novel cross-slot printed wideband conformai antenna is proposed for GPS application. The combination of partial ground plane and cross-slot on the patch are used for bandwidth enhancement. The proposed conformal antenna exhibits a fractional bandwidth(for the definition of −10dB) of 79.28% operating from 1091 to 2524 MHz. The radiation pattern exhibits an omnidirectional pattern and gain of the proposed conformal antenna is 2.37 to 5.33dBi within operating frequency range.

Water is a key resource for life on earth. Clean Drinking water is one of essential human needs. With the increase in urbanization a threat of water scarcity is alarming. This triggers the idea of reuse and recycling of waste water. This paper presents the need for waste water treatment and also gives the brief description of various stages of waste water treatment. The waste water treatment plan works optimally only under certain parameters. Hence sensors can be used at different stages of water treatment for automation. This paper presents the importance and necessity to recycle the waste water and provides a solution for automation of the waste water treatment plant.

Smart cities mission of India gaining popularity day by day. With the introduction of Internet of Things into smart cities the goal of smart cities mission is easy to achieve. One of the key feature of smart cities is Public transport. A smart city should possess an Intelligent public transport system. Today with the lack of appropriate information system in the public transport system, passengers are facing huge problems in the crowded cities. Passengers are forced to wait for long time since they don't know the information of an upcoming Bus or Train reaching to a terminus. With the introduction of technology into the public transport system a passenger can travel with an ease in the city. Here we propose a system where the current position of the buses and the arrival and departure times of the buses can be informed to the passengers via the display boards in the bus terminus or via the app installed in smart phone by incorporating latest technology into existing bus systems. The proposed technology has GPS system that tracks the location of the bus, a sensor incorporated in the bus to know passenger count. The GPS and sensor data is processed by a Raspberry Pi3 computer and then sent to a server. At the Bus terminus this information can be accessed through WiFi/Internet by the passengers.

Nowadays the idea of Smart Cities had become very popular. With the advent of Internet of Things, the concept of smart cities can be readily achievable. An extensive research is ongoing in the field of Internet of Things to increase the quality of services offered in cities and to improve the productivity and reliability of urban infrastructure. Internet of Things is addressing the most common problems faced in cities like availability of car parking and traffic jams. This paper presents an Internet of Things based Parking system for Smart Cities. The proposed parking system contains an IoT module deployed on-site for managing the available parking spaces. A platform provided in the form of portal for booking the parking spaces.

In this paper, a compact, dual-band patch antenna is proposed over Minkowski fractal defected ground structure (DGS) for bandwidth enhancement of global positioning system (GPS) applications. The proposed design combines the truncated dual L-shaped slits cut on diagonal corners of radiating patch and fractal defect on the metallic ground plane. This concept shifts the frequencies to lower bands with improvement in antenna radiation properties. By deploying symmetrical and asymmetrical boundaries to the structure for the fractal DGS on metallic ground plane, improvement in bandwidth and gain are obtained. Compact antenna size is achieved for dual-band GPS frequencies of L1 (1.575 GHz) and L2 (1.227 GHz). The measured results for antenna prototype are (1.2–1.245 GHz): L2 band and (1.51–1.59 GHz): L1 band for 10 dB return loss bandwidth with better pattern radiation. Gain value with and without DGS is observed for compact antenna overall volume of 0.32λ0 × 0.32λ0 × 0.024λ0.

A novel tri-band asymmetric slot with defective ground structure (DGS) microstrip antenna for dual circular polarization (CP) is proposed. By placing a slot with 45° across diagonally at the center of the patch, excites resonant bands with narrow bandwidth and dual CP operation. The main design challenge is to introduce optimized defected element of circular dumbbell shape to enhance the impedance bandwidth with frequency shift operation at all bands. DGS enabled antenna is practically fabricated and simulated. Antenna is compact in size and shows a good quality of CP at two resonant bands and linearly polarized at one band. Structure displays the impedance bandwidth of 8% (2.26–2.45 GHz), 5.45% (3.41–3.6 GHz) and 3.07% (5.12–5.28 GHz). The design also shows 40 and 11 MHz, 3-dB axial ratio bandwidth at lower and middle bands, respectively. Simulated gain for each band is 4.72, 6.2 and 4 dB. Performance of antenna with and without DGS is also studied and compared. This single probe feed proposed antenna remains consistent with good radiation patterns and sufficient antenna gain over the operating bands. Excellent agreement was obtained between measurements and simulations.

In this letter, a compact zigzag-shaped-slit rectangular microstrip patch antenna with circular defected ground structure (DGS) is designed for wireless applications. The probe-fed antenna consisting of a zigzag-shaped slit, dual T-shaped slits on either sides of a rectangular patch, and circular dumbbell-shaped defected ground plane is optimized. The antenna was able to generate three separate resonances to cover both the 2.45/5.28-GHz WLAN bands and the 3.5-GHz WiMAX bands while maintaining a small overall size of $40 \times 28 \times 3.175~\hbox{mm}^3$ . The return-loss impedance bandwidth values are enhanced significantly for three resonant frequencies. The designed antenna is characterized with better radiation patterns and potentially stable gain around 4–6 dBi over the working bands. Good agreement was obtained between measurements and simulations.

The novel approach of this paper describes the suppression of grating lobe level with the element count optimization in planar antenna array. Rectangular lattice (RL) and triangular lattice (TL) structures are chosen for determining the achievable array element patterns (EP) and further suppressing the grating lobe level. The element spacing and number of elements (10 × 20 array) are taken into account for particular lattice. Grating lobe peaks are observed for the 200-element planar array at maximum scan angle (θ) with the set frequency of 3 GHz. Further, it is found that 14°; bore sight elevation of rectangular lattice produces a transformed field of view, which permits a reduction in element count of 20.39% compared with 10° bore sight elevation. Finally, the typical values of elevation, element count and array size (25 cm2) are trained using artificial neural network (ANN) algorithm and element count is predicted after testing the network. The network shows a high success rate.

A novel wideband conformal slot antenna is proposed for GPS application. Initially a planar antenna with dumbbell shape slot on three sides of patch is designed at a slightly higher frequency and then the planar antenna is transformed to the corresponding cylindrical conformal antenna with the desired radius of curvature. The antenna used in this study employs a dumbbell shape slot on the three sides of patch. To design the wideband antenna, combination of partial ground concept and dumbbell shape slots on patch is employed. The flexible and higher thermal stable substrate like Rogers RT/duroid 5880 with permittivity of 2.2 and thickness of 0.787 is used. Microstrip line feeding is used in the proposed antenna. The proposed conformal antenna exhibits a fractional bandwidth (for the definition of −10 dB) of 75.94% operating from 1056 to 2349 MHz, which is suitable for all GPS band, GLONASS and GALILEO application. The radiation pattern exhibits an omnidirectional pattern and gain of proposed conformal antenna is 2.09 to 4.9 dBi within operating frequency range.

A novel conformal antenna is proposed for GPS application using Koch fractal geometry. The conformal antenna is obtained by initially designing planar patch antenna at a slightly higher frequency by using Koch fractal and then the planar structure is transformed to the corresponding cylindrical conformal antenna with the required radius of curvature. The Rogers RT/duroid 5880 with permittivity of 2.2 and thickness of the material 0.787mm is used as substrate. Coaxial probe feeding is used in the proposed antenna. The proposed cylindrical conformal is having a bandwidth of 20MHz and also has a peak gain of 5.9dBi at the center frequency of 1.575GHz. The conformal antenna designed on the 60mm radius of curvature at 1.575GHz that can be used for GPS application which can accommodate L1(1.56–1.58GHz) band.

In this study, a dual band-notched ultra-wideband tapered slot antenna is introduced. Here, split ring resonator and balun are used to suppress spurious unwanted bands. The split ring resonator is etched to the certain distance from the excitation point. Hence, one resonance is excited with extended band width. According to the feeding configuration, the stepped microstrip line and slotline connected with circular slot. So, strong EM wave coupling is generated with balun. The electric-field-coupled (ELC) resonator structure is placed inside the circular balun. The size of the tapered slot antenna is 55×40 mm2. The simulation results show that the impedance bandwidth of the antenna is covered an ultra-wideband frequency range (3.1 to 11 GHz) with VSWR< 2 and the band rejection is created at WLAN and ITU band.

In this paper MIMO transmission scheme is analyzed with pre-ordered ZF-SIC, MMSE-SIC and ML detection schemes by transmitting BPSK modulated symbols over Rician-K, Nakagami-m fading channels. Rician-K fading channel is proper medium whenever there is LOS component between transmitter and receiver. Nakagami-m fading is most generalized channel model. it can generate any other channel model by changing shaping parameter m. and BER vs. SNR graphs are generated for Rician factor K = 4, 8. Nakagami m = 1, 1.4 and 1.8 and performance of three detectors is compared.

A novel compact multi-band microstrip antenna is proposed in this paper. The antenna structure is made to resonate at multiple frequencies by introducing two small rectangular strips attached vertically at the edge of a conventional rectangular patch antenna. The designed antenna resonates at S and C bands. The final optimized dimensions of the basic rectangular patch antenna are 40 x 15 mm and two rectangular strip lines are spaced at 2.5 mm with different dimensions. The simulated antenna shows that the return loss of the proposed antenna at resonant modes are lower than -10 dB. For multi-band applications, the simulation results provide good performance in term of return loss as well as radiation pattern.

A compact single probe feed Minkowski fractal boundary patch antenna based on HIS (High Impedance Surface) is proposed for dual band dual polarization operation. Dual band operation with widened bandwidth at each resonating frequency and dual polarization can be achieved by using the combination of HIS and Minkowski fractal curves. The 10-dB return loss bandwidth of lower and upper frequency bands are 13.01% and 4.95% respectively. The 3-dB Axial Ratio bandwidth is 3.4%.

A novel approach to design Multiple Function Antenna (MFA) arrays using Artificial Neural Networks is suggested. A planar array with uniform current excitations which can generate different beam widths and gains is designed using Artificial Neural Networks. The desired beam width, gain and number of elements are given as input to the neural network. The output of the neural network is the current excitations in the form ON/OFF state of the array. Radial Basis Function Neural Network (RBFNN) is initially trained with the input-output data pairs and tested. The network showed 98% high success rate.

A novel planar and conformal antenna with dual U slot are proposed at 2.41GHz and 2.45GHz respectively. The antenna is designed on RT Duroid 5880 substrate of permittivity 2.2 and thickness of 0.787mm with microstrip inset feed. The proposed planar antenna also has bandwidth of 24.9MHz and has maximum gain of 4.2dB. The planar antenna is transformed to conformal cylindrical of 25mm, 45mm and 60mm radii. The gain values are decreased from 5.9dB to 2.81dB but the bandwidth values varies from 23MHz to 22.1MHz by changing the radius of curvature from 60mm to 25mm. The planar and conformal antenna on different radii has a single band at 2.41GHz and 2.45GHz respectively which is suitable for Wi-Fi application.

In the present work, an optimized approach is described in predicting the current excitations of a planar array geometry for obtaining multiple beam widths in a single aperture using Radial Basis Function Neural Network (RBFNN). The approach utilizes current distributions of uniform, binomial and triangular forms for a 5×5 planar array. The radiation pattern values are given as input to the neural network. The output of the neural network is current excitations of the planar antenna array elements. RBFNN is initially trained with the input-output data pairs and tested and explored for the estimation of current excitations. The network showed a high success rate.

A novel probe feed dual polarized pentagon slot shaped planar antenna is designed and proposed supporting wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications simultaneously. Structure comprises of pentagon shaped radiating element along with scaled down slot cut on center of patch, having overall compact size of 40×40mm2. The conventional pentagon patch resonates at 3.5GHz and the modified slot based structure resonates at tri bands of 2.4/3.5/5.2GHz. Effective comparison of antenna with and without pentagon slot is performed to obtain better impedance bandwidth, acceptable gain at operating frequencies and circular polarization at 2.4GHz. The simulated results exhibit the designed antenna operates over triple frequency ranges, fulfilling the standards of WiMAX and WLAN. Gain values obtained are 5.6, 3.2, 2.04dB respectively over respective tri bands. In addition, acceptable radiation characteristics are obtained over the operating bands.

A method to diagnose on-ofi faults in a planar antenna arrays using far fleld radiation pattern is presented. A systematic approach is suggested for detecting location of faulty elements using Artiflcial Neural Networks (ANN). Radial Basis Function neural network (RBF) and Probabilistic neural network (PNN) are considered for performance comparison.

A systematic method for the diagnosis of planar antenna arrays from far fleld radiation pattern using neural networks is presented. Two types of neural networks, Radial basis function (RBF) and Probabilistic neural network (PNN) are considered for the performance comparison. Deviation pattern is used as input to the neural network to determine the location of the faulty element and error in excitation.

This paper presents a new patch antenna array which generates single, dual and multi bands that are capable of maintaining high performance over a wide spectrum of frequencies. This antenna incorporates a simple and novel single layered pentagonal slot antenna to achieve different resonant bands. For feeding the antenna and array elements, an inset line feed network is used. Structures are realized using IE3D simulation tool and implemented using commercial substrate to meet low cost requirements. Appropriate impedance matching is achieved at different bands of single element, 2×1 linear array and 2×2 planar arrays with proper designed transformation. High impedance bandwidths, moderate gain and better efficiencies are obtained as outcomes from the analyzed configurations, compared to existing designs. Peak antenna gains for three cases are about 5dBi, 6dBi and 9 dBi have been obtained for different resonant bands, respectively.

This paper describes a corrugated antipodal Vivaldi antenna with improved performance by using negative index metamaterial (NIM) of the Archimedean spiral design. A single layer NIM piece is placed perpendicular middle of the two arm of the proposed antenna. The antenna size is 30×60×0.787 mm3 operating at 8GHz. The simulated results of NEVI corrugated antipodal Vivaldi antenna show that the gain and directivity has increased up to 1.2dB and 1dB respectively. The HPBW is increased by 90 with the reflection coefficient less than DIO dB from 4.7 GHz to 11 GHz for UWB application.

Single probe feed triangular patch antenna with asymmetric dual V-shaped slots is designed, fabricated and tested for tri-band applications. The unequal length arms of inner and outer V-slots gives provision to achieve two degenerate orthogonal modes, which lead to circular polarization (CP) at lower and middle bands respectively. The antenna resonates at frequencies of 2.4GHz, 3.5GHz with CP and 5.28GHz with linear polarization (LP). Good agreement obtained between simulated and measured results.

Compact microstrip patch antenna with L-shaped spur lines using Hilbert shaped fractal defective ground structure (DGS) is proposed and investigated for multiband applications. The objective of the paper is to obtain average size reduction of about 72% using resonant frequency shift method with the help of DGS. The impedance bandwidth, gain and efficiency are observed and compared for the proposed antenna with and without DGS. Excellent agreement is found between simulated and measured results.