In this paper, we discuss how to control the side lobe level of corrugated metallic periodic leaky wave Antenna by its artificial surface impedances. Leaky Wave Antenna have beam steering ability by Frequency Scan or by artificial Surface Impedance control in the constant frequency. side lobe level of Leaky Wave Antenna is Worse level of Antennas side lobe levels and This level worst if other Modes of Leaky wave antennas is activated. Therefore just minimize the side lobe level as well as. By applying the coefficients calculated by Taylor's method to the parameters of the leaky wave antenna (M and, accordingly, the depth of the teeth), the antenna was designed, simulated, built and evaluated and tested. The result of controlling the side lobelevel in this article is to reach the SLL of 18dB in the simulation, while in practice we reached the SLL of 16 dB in the measurement of the antenna made at 10 GHz frequency.

n this paper, a X-band beam steerable non-uniform reflectarray antenna is proposed. The-10dB power beamwidth and side lobe level of the proposed antenna are respectively 17° and-18dB which show significant improvement proportional to previous works. The beam steering is carried out with a small movement of a large element, i. e. the ground plane of the antenna. It is shown that the ground plane movement has negligible effect on the reflectarray phase characteristic, as a consequence of the proportionality between reflectarray phase distribution and element phase variation. This ensures that the distortion of far-field pattern is avoided. About ± 10° tilt of antenna beam from the broadside is achieved with ± 0. 05λ ground movement. In the proposed structure beam steering capability is provided using passive elements which eliminates the problems of using active circuits such as bias difficulties, component losses and low power handling. After describing design procedure completely, the proposed antenna is simulated with an electromagnetic full-wave software and the results are validated.

A side lobe Canceller (SLC) structure is a conventional partially adaptive technique which is used in large adaptive array radars. If a desired signal has long time duration in comparison with the SLC adaptation time, signal components may be cancelled. So, this paper presents a modified SLC which eliminates desired signal cancellation problems and allows using an unconstrained adaptive algorithm. Simulation results demonstrate the performance of this modified structure for a planar array.

In this paper we describe the design and evaluation of Vivaldi elements optimization ‎for operation in the array environment over a wide range of frequency (12-18GHz). ‎The Finite Difference Time Domain (FD TD) is used in design and analysis of finite ‎Vivaldi array and genetic algorithm (GA) for optimization of its radiation pattern. The ‎hybrid method is used to find maximum side lobe level (SLL) over a range of ‎frequency (12-18GHz) by adjustment of the antenna and array parameters. An array ‎SLL improvement of MB was attained by optimization. Here a single Vivaldi antenna ‎and a four-element array are analyzed and compared with measurements. Theoretical ‎and experimental results show good agreement with each other.‎

Always antenna structures with low sidelobe levels are a main goal during antenna design. In this paper, a new method for reduction of radiation patter sidelobe level in phased array antenna with uniform and non-uniform weighting is presented. In this method, by change of array elements weight or adding several elements, such as SLC technique, the pattern with low side lobe level can be achieved.According to the design, in an array with uniform weighting value of SLL in third sidelobe to next more than -10 dB can be reduced so that main beam-width changes less than %3 and variations of gain is negligible.Since in applications use non-uniform weighting so, here a new method for sidelobe level reduction in phased array antennas radiation pattern by Taylor weighting is presented. In this method, by use of uniform weighting results, the weight vector of array modify so that sidelobe reduction in resultant pattern is perceptible. In this method, the value of SLL in third sidelobe to next, ratio to primary Taylor weighting can be reduced so that main beam-width approximately %1 to %2 changes and variation of array gain is negligible. Since in phased array antennas, location of main-lobe can be set electronically by applied proper phase in arbitrary angle, performance of this method in pattern scanning is considered and shown in both way that this method is independent from main-lobe location.

Antenna structures with low side lobe levels are normally the main goal during antenna design. In this paper, a new method for reduction of radiation pattern side lobe level in phased array antenna with uniform and non-uniform weighting is presented. In this method, by changing the array elements weight or adding several elements, such as SLC technique, the pattern with low side lobe level can be achieved. According to the design, in an array with uniform weighting, the value of SLL in third side lobe to next more than -10 dB can be reduced so that main beam width changes less than 3% and variations of gain is negligible. Since in applications non - uniform weighting is used, here a new method for side lobe level reduction in phased array antennas radiation pattern by Taylor weighting is presented. In this method, by use of uniform weighting results, the weight vector of array modify so that side lobe reduction in resultant pattern is perceptible. In this method, the value of SLL in third side lobe to next, ratio to primary Taylor weighting can be reduced so that main beam width approximately 1-2% changes and variation of array gain is negligible. Since in phased array antennas, location of main lobe can be set electronically by applying proper phase in arbitrary angle, performance of this method in pattern scanning is considered and shown in both ways that this method is independent of the main lobe location.

The main purpose of this paper is to modify the holographic technique relationship (formula) and to present an algorithm for the design of multiple frequency compact leaky-wave antennas with broadside pencil beam radiation. In the design process, the following three software HFSS, MATLAB and CST, have been utilized. As a prototype, a triple frequency planar leaky-wave antenna is designed with the SLL less than-15 dB at E and H planes and broadside pencil radiation gain of 17. 9, 18. 5 and 19. 2 dB at 15, 16 and 17 GHz, respectively. The unit cell forming the impedance surface of the hologram is selected as a regular hexagon to have the most isotropic behavior in response to the surface wave. Modification of the holographic relationship leads to the possibility of using a surface wave feed with a simple structure for proper matching as well as controlling the SLL on the E and H planes of the antenna radiation pattern at the designed frequencies. Eventually, by constructing and testing the proposed antenna, the accuracy of the proposed design process has been verified. In measuring the radiation pattern of the E and H planes of the different frequencies in the antenna room for each frequency, the launcher corresponding to that frequency receives the excitation and the other two launchers are perfectly matched. Finally, a good agreement is observed between the simulation and measurement results.

Transmit waveform design is one of the most important problems in active sensing and communication systems. This problem, due to the complexity and non-convexity, has been always the main topic of many papers for the decades. However, still an optimal solution which guarantees a global minimum for this multi-variable optimization problem is not found. In this paper, we propose an attracting methodology to design transmit waveform of active sensing and communication systems with good auto-correlation properties. To this end, we tackle the non-convex optimization problem of Integrated sidelobe level (ISL) minimization with the unimodular constraint. Using the epigraph and Second Order Cone Programming (SOCP) approach, the in-hand non-convex optimization will resort to a Semi-Definite Programming (SDP). Then, we use Majorization-Minimization to deal with constraints and convert the obtained problem to a convex optimization problem. Finally, the obtained optimization problem is tackled using CVX toolbox. To obtain the code vectors from the extracted optimal code matrix, we use rank-one decomposition. The simulation and results indicate the powerfulness of the proposed algorithm in designing radar transmit sequences with unimodular constraint. We show the proposed algorithm can design long length sequences with a very small ISL values. The proposed framework further can be investigated for the future optimization problems, like Peak side lobe level (PSL) minimization.

In the modern era, the antennas with cosecant squared pattern play a significant role in radar applications. These applications are used to cover an airspace to search for targets and estimate their height. In this article, a method is proposed for the synthesis of cosecant squared pattern using leaky wave antenna. The principal mechanism in the leaky wave antennae is wave attenuation due to power leakage while the wave propagates through the structure. Thus, by controlling the leakage and phase constants along the length of the structure, one can synthesize the desired radiation patterns. We have used the genetic algorithm to optimize the leakage constant and obtain the desired cosecant squared pattern In the range of 10 to 30 degrees. Conformity in simulation results and measured results indicates accuracy in the design process. The proposed method obtains the desired pattern with a ripple of less than 2 dB in the designated area and side lobe level less than-18 dB, which makes the antenna suitable for radar applications.