A novel approach to ultra-wideband (UWB) antenna design is presented which is based on a general description for the geometry of monopole antennas. This general description is capable of producing almost all possible shapes for monopole antennas and it is compatible with different optimization methods. The general description is used for the optimization of rotationally-symmetric monopole antenna with finite ground plane. The optimization of antennas is performed by applying a hybrid procedure, which begins with a global search and completes with a local optimization. The optimization procedure aims at minimizing the reflection from antennas while reducing the distortion of radiated pulses. In some cases, the reduction of variations in the energy pattern is also considered. The numerical results show the reliability and effectiveness of the whole process and considerable improvement in comparison with similar antennas reported in the literature.

In this paper, with the aid of Galerkin's method and integral equations of electric field, full wave analysis applies on wraparound microstrip antenna, which its result, is reach the parameters as input impedance, radiation frequency and radiation pattern. Also, in addition of the above result, a parallel feed network is designed, using the Tacheston software.

In recent years reflectarray antennas have received considerable attention due to their unique capabilities. However, due to their large size, analyzing the performance of these antennas using traditional full wave finite-difference and finite-element techniques requires considerable computational resources. In this paper, we present an efficient method to accurately analyze these class of antennas which considerably reduces the computational burden. First, the radiation properties of the unit cells of the antennas are obtained by applying periodic boundary conditions, which corresponds to an infinite array. Then, a phase-only algorithm is used to obtain required phase shift on the antenna surface. Next, different unit cells are used to achieve the required phase on the antenna surface. Lastly, to confirm the validity of our approach, each designed antenna is simulated by full wave method using method of moment and the full wave simulation results of co and cross polarization levels are compared with those obtained using the proposed formula. There is excellent agreement between the co- and cross polarization levels obtained by proposed approach and those obtained using full wave simulation.

In recent years, the plasma antenna is a new technology for replacing the metal antennas that have been designed with better performance. In the steady state, the radiation pattern of a plasma antenna will be similar to the case of metallic antennas with the same form, size and performance at the same frequency and power. By sweeping the parameters in the plasma tube, we can change the operating frequency without changing in the antenna length. The most of designs have been investigated only on the basis of the practical experiment. In this paper, a step by step procedure is presented for the design and simulation of a plasma antenna and its material. Also, a new design for the coupler shows that in addition to transmit and receiving signal with the inner coupler, there is no electromagnetic interference (EMI) due to the outer shell. Based on the design procedure, the simulation and implementation of the antenna is performed and tested in VHF band. The measurement results are compatible with the simulation excellently.

In this paper, a pen-shaped antenna, called Vlasov antenna, is introduced. This antenna has a simple structure and can be constructed by creating a slant at the end of a circular waveguide. The main property of this antenna is its suitable radiation by excitation of some modes such as TM01, which are symmetrical. The analysis of the antenna is done qualitatively and then the manner of its design is introduced. A pen-shaped antenna is designed in the X band and then is simulated, fabricated, and its performance is measured.

In this paper, a four-band microstrip antenna using metamaterial structure is presented. The antenna proposed in this article, has an asymmetric structure and it is made up of two identical radiation elements and ground plane at the back. In this design, each radiation element consists of a reciprocating capacitor, which is attached to a slotted triangular acetate at the end. The proposed antenna has a miniature dimension of 10×15 mm2. Also the proposed antenna has four resonances in frequencies of 3. 19 GHz (1. 25%), 6. 22 GHz (10. 74%), 7. 18 GHz (5. 19%) and 9. 12 GHz (4. 52%). Pattern and gain of the antenna are acceptable at resonant frequencies and the good consistency between the test result and the simulation confirm the accuracy of the antenna design. The proposed antenna is made and tested in the antenna laboratory. The results of the measurements are presented in the paper. Good consistency between test and simulation results confirms the accuracy and efficiency of the proposed multirole microstrip antenna design.

In this paper, the minimax optimization method has been proposed to design the shaped dual reflector antenna for being used in the geostationary satellite (GEO). For this purpose, the distortion on the reflector surface is considered with an expansion of B-spline functions and the coefficients of expansion are obtained using the minimax optimization method. In comparison with other optimization methods, which are based on evolutionary algorithms that prolong the antenna design, this is a gradient-based method and significantly accelerates the antenna design. In the minimax optimization method, there is a need for calculating the derivatives of the optimization fitness function compared to the problem variables. Thus, in this paper, the derivative of the fields calculated by physical optic have been analytically calculated compared to the reflector surface variables. A comparison of the simulation results and implementation time of two minimax methods with the genetic algorithm indicates the high efficiency and rate of minimax method.

In this paper, a new leaky wave antenna (LWA) is introduced. The proposed antenna radiates through a dielectric aperture created by half mode substrate integrated waveguide (HMSIW) technique. A sample antenna is designed and simulated and its radiation characteristics are investigated. It is illustrated that half conical radiation pattern is provided by the proposed antenna. The designed antenna is also fabricated and its radiation properties are measured. Results show that the proposed antenna has the advantages of wide bandwidth, enhanced scanning angle and high gain in addition to low profile, low fabrication cost, low weight. Radiation patterns of antenna at different frequencies are theoretically calculated and compared with simulated ones. Good agreement between simulated and calculated results proves the validity of the theory presented for the calculation of radiation patterns. Moreover, its common features including high directivity and beam steering capability which make it suitable for millimeter-wave applications.

The sinuous antennas have a numerous applications in military and civil systems such as direction finding, research and measurement laboratories and reflector feeds; which are due to their superior broadband characteristics and simultaneous right and left hand circular polarization. These capabilities are most required in radars and aerospace applications. Although, the sinuous antenna size, bandwidth, and radiation parameters are the same as spiral antenna, due to complex structure and complicated feeding network, the sinuous parameters do not investigated accurately.In this paper, a comprehensive survey on the antenna parameters has been proposed. Based on these studies, design, construction and measurements of an optimized planar sinuous antenna for 1–5 GHz frequency range have been presented.

In this paper, a new CPW (Coplanar Waveguide) fed printed UWB antenna integrated with a narrowband antenna is designed and analyzed for cognitive radio applications. The ultra-wideband (UWB) and narrowband (NB) antennas provide bandwidth from 2. 2 GHz to 11GHz and from 4. 8 GHz to 5. 7 GHz respectively and reasonable isolation between the antennas. A prototype of the integrated antenna was fabricated and its performance was verified. The dimensions of the FR4 substrate are 40 × 48 × 1. 6 mm3. The antenna represents good radiation characteristics, stable gain and good time domain manner to deliver the requirements of the current wireless communication standards. Also, two external tuning circuits were designed to show the ability of the narrowband antenna for reconfiguration.