A New Linear Printed Vivaldi Antenna Array with Low Side Lobe Level and High Gain for the Band 3.5 GHz

This paper proposes a new design of low sidelobe level (SLL) and high gain linear printed Vivaldi antenna array. The array composes of two parts, which are a linear Vivaldi antenna array and a back reflector. The array consists of 10 single Vivaldi antennas and a series-fed network, those are based on Roger RO4003C substrate (ε = 3.55) with the dimension of 140 x 450 x 1.524 mm3. A new Bat algorithm with the amplitude-only control technique has been applied to optimize the output coefficients of the series-fed network for gaining a low SLL. The simulation results indicate that the proposed antenna provides a low SLL of -29.2 dB in E-plane with a high gain of 16.5 dBi at the frequency of 3500 MHz. A prototype of the proposed antenna array has been fabricated. The measured data has a good agreement with the simulated data

BAT Algorithm Based Beamformer for Interference Suppression by Controlling the Complex Weight

In this study, an adaptive beamformer for pattern nulling of Uniformly Spaced Linear Array (ULA) antennas, which utilized BAT algorithm (BA) to suppress interferences, has been proposed. This pattern nulling has been obtained by controlling the complex weight (both the phase and the amplitude) of each array element. So as to verify the proposal, a number of scenarios of ULA pattern imposed the pre-set nulls have been carried out and compared with those of accelerated particle swarm optimization (APSO). The proposed beamformer has demonstrated the capability to place with precise single, multiple, and broad nulls at arbitrary interference directions, suppress side lobes, and maintain a predefined beamwidth. Moreover, the beamformer shows faster convergence and higher efficiency regarding null steering and side lobe suppression in pattern synthesis, as compared with an APSO based beamformer

A Novel Chebyshev Series Fed Linear Array with High Gain and Low Sidelobe Level for WLAN Outdoor Systems

This paper proposes a novel high gain and low sidelobe level (SLL) linear microstrip array antenna for outdoor WLAN applications. The antenna consists of two main parts, which are a linear array and a reflector. The linear array comprises of 10 elements; those have been designed on Rogers RT/Duroid 5870tm with the dimensions of 422×100×10.15 mm3. To gain low SLLs, a series fed network was designed to have the output signals being proportional to the Chebyshev distributions (with preset SLL of -30 dB). Furthermore, Yagi antenna theory has been applied by adding directors above every single element to increase the directivity of the single element. The reflector has been constructed at the back of the proposed structure. Simulation results show that the array can provide high gain of 17.5 dBi and a low SLL of -26 dB. A prototype has been fabricated and measured. Good agreements between simulation and measurement data have been obtained

The Unified Approach to the Analysis of Spherical Multilayer Structures and its Applications

This work presents a unified procedure to analyze radial waveguides, dielectric resonators, dielectric resonator antennas and microstrip antennas on spherical structures. It can be applied to any type of spherical multilayer closed and sector structures, which also include hemispherical structures. The arbitrary layers may be air or dielectric substrates with or without metallizations in the interfaces. The inner layer can be a metallic or dielectric core. The kernel of this approach is the derivation of the spectral- and space-domain dyadic Green’s function of spherical multilayer structures by using an equivalent circuit and simple network analysis techniques. The relations between the spectral and space domains are derived using the vector-Legendre transformation. The verification process of this approach is done on some test structures. For dielectric resonators, the system equation of a two-layer dielectric resonator is analytically verified with literature, the resonant frequencies of a resonator with two dielectric substrates covering a metallic core agree well with commercial software. For microstrip antennas, the dyadic Green’s function of a microstrip antenna on a spherical structure of one dielectric layer covering a metallic one is identical to literature and very good agreement of the input impedance and radiation pattern of the antenna with commercial software codes is achieved. The agreement of the calculated input impedance of microstrip antennas with measured data is also obtained. The effects of the curvature and ground plane on the input impedance and radiation pattern are shown. Furthermore, the derivation of system equations of some commonly used radial waveguides and the dyadic Green’s function of some more complex microstrip structures are presented

Analysis method of microstrip antennas on hemispherical multilayer structures

A generalized method for the analysis of microstrip antennas, which are placed on or embedded in hemispherical multilayer structures, is presented. By using corresponding fullwave equivalent circuits, the dyadic Green’s functions of these structures and their system equations for the tangential field components at the interfaces can be analytically derived in a simple way. The numerical results are verified with commercial software codes. Some effects of the curvature and the ground plane on the input impedance of microstrip antennas are shown