Themistoklis D. Dimousios

Design and optimization of a multipurpose tri-band Electronically Steerable Passive Array Radiator (ESPAR) antenna with steerable-beam-pattern for maximum directionality at the frequencies of 1.8, 1.9 and 2.4 GHz with the aid of genetic algorithms

The development of ESPAR antennas is a progressing research area which will play a significant role in commercial mobile communications applications. In this paper the performance of an electronically steerable passive array radiator (ESPAR) antenna, with cylindrical skirt regarding the horizontal radiation pattern, suitable for both mobile telephony (1.8 and 1.9 GHz) and WiFi/WLAN (2.4 GHz) applications is presented. An effort is carried out to optimize the performance of this structure regarding its resonant frequencies and the formation of a directional beam to a predetermined direction with the aid of the genetic algorithms (GA) technique. Due to their limited physical size, these antenna systems can be developed for application in the areas of mobile telephony, WiFi and ad hoc wireless networks.

A Broadband, Vertically Polarized, Circular Switched Parasitic Array for Indoor Portable DVB-T Applications at the IV UHF Band

In this paper, a new broadband, vertically polarized, circular switched parasitic antenna array, appropriate for portable DVB-T applications at the IV UHF band, is developed with the aid of a proposed genetic algorithm approach. The array consists of a central fixed parasitic element and four peripheral ones. At any given time, only two adjacent peripheral elements are active, while each of the remaining two is short-circuited. By appropriately selecting active and short-circuited elements, a set of four radiation patterns can be formed, covering the horizontal plane alternately. Design considerations and results are presented, while array measurements are demonstrated for a single snitching mode.

Design of a Corner-Reflector Reactively Controlled Antenna for Maximum Directivity and Multiple Beam Forming at 2.4 GHz

Electronically steerable passive array radiator (ESPAR) antennas constitute a promising research field and are expected to play important role in future wireless communications. In this paper, a new approach in ESPAR antenna design for base station applications is proposed. A corner-plate reflector is combined with active and passive (reactively loaded) elements in order to implement a corner-reflector ESPAR (CR-ESPAR) configuration. It is shown that when combined with corner reflectors in order to sectorize the coverage area, an ESPAR antenna offers multiple radiation patterns with higher directivity and resolution. A case study of a CR-ESPAR suitable for 2.4 GHz ISM applications is demonstrated, where the performance of the structure is optimized with respect to resonance frequency, input impedance, and multiple switched-beam patterns configuration. The optimization of the array is performed using a Genetic Algorithm (GA) tool as a method of choice, achieving a maximum gain equal to 14 dBi for a 30°3 dB-beamwidth and a gain of 11 dBi for a 45°3 dB-beamwidth, while the VSWR is kept below 1.7 in all cases. Due to its limited physical size, the proposed CR-ESPAR can be used as a portable antenna for deployment in WiFi, WLAN and other applications.

A circular switched parasitic array of log-periodic antennas with enhanced directivity and beam steering capability for ultra wideband communications applications

In this paper a circular switched parasitic array of log-periodic dipole antennas (LPDAs) is introduced. The overall structure is subjected to an optimization procedure in order to attain significant directivity and operational bandwidth at the 3.1 GHz - 10.6 GHz frequency band with the aid of the genetic algorithms technique. Beam steering is feasible by selecting which one LPDA is connected to the signal source.

Analysis and Design of a Broadband Circular Switched Parasitic Array above finite plate and finite plate with skirt

The circular switched parasitic array (CSPA) is a smart antenna system promising to play an important role in mobile systems manufacturing. In this paper, an effort to optimize the overall structure of a five-element monopole CSPA above a square wire grid plate in order to form a desired radiation pattern and achieve impedance bandwidth at the V UHF band is carried out utilizing the genetic algorithms (GA) optimization technique. The resulting configuration is then compared with the same monopole array placed above a wire grid plate with skirt.

Design and Optimization of a Switched Parasitic Corner Plated Antenna for maximum Directionality and Diversity Gain at the WiFi frequency of 2.4 GHz with the aid of Genetic Algorithms

The development of switched parasitic arrays is a progressing research area which will play a significant role in commercial mobile communications applications. In this paper, a switched parasitic corner plated antenna suitable for WiFi (2.4 GHz) applications is presented. An effort is carried out to optimize the performance of this structure regarding its resonant frequency and the formation of a directional beam to a predetermined direction with the aid of the genetic algorithms (GA) technique.

A PIFA - parasitic optimization utilizing the Genetic Algorithms technique

The development of integrated antennas is a progressing research area which plays an important role in commercial mobile communications applications. In this paper, a structure consisting of a planar inverted F antenna and a parasitic element above the same ground plane (PIFA - parasitic) is presented. An effort is carried out to optimize the performance of this structure regarding its resonant frequency and bandwidth. With the use of the genetic algorithms (GA) optimization technique, a PIFA - parasitic with frequency - independent operational characteristics is presented and a sufficient impedance bandwidth is achieved.

A simple switched parasitic array with a fixed active element for WiFi and WLAN applications at 2.4 GHz

In this paper the case of a switched parasitic array with the active element fixed in order to form a directional beam to a predetermined direction and achieve resonance at 2.4 GHz is examined. A structure with five elements and a structure with seven elements are presented. Due to their low geometry profile, these antennas can be implemented for operation in the areas of WiFi and WLAN networks.

A New, Compact, Low Cost Switched Beam Array for ISM and WLAN Applications at 2.4 GHz

A low cost and profile switched beam array suitable for 2.4 GHz ISM and WLAN applications is proposed in this paper. The array comprises eight wire elements lying on the horizontal plane and a set of four possible, switching, beam patterns is provided. Sufficient front gain and input impedance matching is achieved with the aid of a simple genetic algorithm.