Improvement of elevation directivity for ESPAR antennas with finite ground plane

Ojiro, Y.; Kawakami, Haruo; Gyoda, Koichi; Ohira, Takashi

doi:10.1109/aps.2001.959390

Cited by 15 publications

(8 citation statements)

References 1 publication

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“…The ground skirting is used to reduce the radiation lobe elevation that exists due to the finite ground plane dimensions [9], [10]. Indoors, ceilings often provide unobstructed reflections, thus reducing the main-lobe elevation not only increases the azimuth gain, but also reduces the likelihood of multipath interference.…”

Section: Espar Antenna Configurationmentioning

confidence: 99%

Seven-element ground skirt monopole ESPAR antenna design from a genetic algorithm and the finite element method

Schlub

Ohira³

2003

IEEE Trans. Antennas Propagat.

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137

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The design of an optimized Electronically Steerable Passive Array Radiator (ESPAR) antenna is presented. A genetic algorithm using a finite element based cost function optimized the antenna's structure and loading conditions for maximal main lobe gain in a single azimuth direction. Simulated gain results of 7.3 dBi at 2.4 GHz were attained along the antenna's elemental axis. The optimized antenna was fabricated and tested with the corresponding experimental gain better than 8 dBi. The 0.7 dB error between simulated and measured gain was constant for numerous structures and therefore did not affect the optimization. The optimized antenna reduced average main lobe elevation by 15.3 to just 9.7 above the horizontal.

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Section: Espar Antenna Configurationmentioning

confidence: 99%

Seven-element ground skirt monopole ESPAR antenna design from a genetic algorithm and the finite element method

Schlub

Ohira³

2003

IEEE Trans. Antennas Propagat.

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137

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“…It is generally considered effective to increase the ground plane size significantly if tilt is avoided in order to obtain radiation elevation toward the horizontal direction. In the ESPAR antenna case, there is a way to realize horizontal radiation with a limited ground plane size by making the ground plane in a cylindrical skirt shape (with a radius of a half-wavelength and height of a quarter-wavelength) [14,24].…”

Section: Finite Ground Plane and Equivalent Steering Vectormentioning

confidence: 99%

Electronically steerable parasitic array radiator antenna

Ohira

Iigusa

2004

Electron Comm Jpn Pt II

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SUMMARYThe electronically steerable parasitic array radiator antenna consists of one feed radiating element and parasitic radiating elements placed in the near field of the active radiator. A beam is formed due to spatial electromagnetic field coupling among radiating elements. The radiation pattern is electronically controlled by means of the variable capacitance devices (varactors) loading the parasitic elements. Unlike a conventional phased array, only one transmitter and receiver are needed for system configuration. Therefore, adaptive beamforming of low dissipation power and low fabrication cost can be achieved. On the other hand, there is only one output port to observe the signal and the weights can be controlled indirectly via reactors instead of direct control. In addition, due to interelement mutual coupling and the parasitic element being directly connected to the reactive device, the linear adaptive array theory developed to date cannot be applied straightforward. In this paper, the configuration of this antenna, its operating principle and formulation, and its measurement method, control scheme, and applications to signal processing are presented. We describe a mathematical model to simulate the radio frequency behavior of the antenna, the equivalent weight vector used for formulation of the characteristics, the admittance matrix including varactors, the effective element length, the equivalent steering vector method, the method for effectively extending the variable range of the capacitance of the varactor, the reactance circuit to cancel nonlinear distortions, the method for calibration of varactors and radiation pattern by measurement of near field of the radiating element, the learning criteria used to control radiation patterns autonomously in adaptation to the electromagnetic environment, the reactance optimization algorithm, the concept of the reactance domain signal processing and the direction of arrival estimation based on such a process, and diversity reception and spatial correlation.

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“…To reduce optimization time, element structural variables were kept within limits that were determined by available material and the overall size of the antenna. The monopole elements were kept at 1 mm radius while the ground skirt was assumed a two-dimensional shape (0 mm thickness) in the simulation process as this parameter was assumed not to significantly influence the behavior of the antenna [8].…”

Section: A Structural Optimizationmentioning

confidence: 99%

Dielectric embedded ESPAR (DE-ESPAR) antenna array for wireless communications

Ireland

Schlub

2005

IEEE Trans. Antennas Propagat.

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A novel dielectric embedded electronically steerable passive array radiator (ESPAR) (DE-ESPAR) antenna array for mobile wireless communication terminal is developed by finite element method based numerical modeling technique. The size reduction of the seven-element monopole antenna was accomplished by embedding the array in a cylindrical rod of FIK ceramic complex with a relative permittivity around = 4 5. Dielectric embedded prototypes of a seven-element ESPAR antenna array were modeled and experimentally characterized. Experimental and numerical results are in good agreement. The optimized antenna produced a horizontal directivity of 5.1 dBi and return loss of 19 dB at 2.48 GHz. An overall volume reduction of 80% and footprint reduction of 50% were achieved.

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Improvement of elevation directivity for ESPAR antennas with finite ground plane

Cited by 15 publications

References 1 publication

Seven-element ground skirt monopole ESPAR antenna design from a genetic algorithm and the finite element method

Seven-element ground skirt monopole ESPAR antenna design from a genetic algorithm and the finite element method

Electronically steerable parasitic array radiator antenna

Dielectric embedded ESPAR (DE-ESPAR) antenna array for wireless communications

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