[天线]40 Antenna Miniaturization and Bandwidth Enhancement Using a Reactive Impedance Substrate

IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 52, NO. 9, SEPTEMBER 2004 2403 T9Juq6|  
Antenna Miniaturization and Bandwidth Enhancement Using a Reactive Impedance Substrate Rky]F+J  
Hossein Mosallaei, Senior Member, IEEE, and Kamal Sarabandi, Fellow, IEEE O]@#53)Tz  
Abstract—The concept of a novel reactive impedance surface Z10}xqi!X  
(RIS) as a substrate for planar antennas, that can miniaturize HNBmq>XDc  
the size and significantly enhance both the bandwidth and the ! {G0'  
radiation characteristics of an antenna is introduced. Using the Bh cp=#  
exact image formulation for the fields of elementary sources -XV+F@`Md  
above impedance surfaces, it is shown that a purely reactive 76<mP*
5  
impedance plane with a specific surface reactance can minimize u|M
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the interaction between the elementary source and its image in the 2 Kjd!~Z$  
RIS substrate. An RIS can be tuned anywhere between perfectly Q35\w
Q#  
electric and magnetic conductor (PEC and PMC) surfaces offering 3s%ND7!/  
a property to achieve the optimal bandwidth and miniaturization H2Wlgt  
factor. It is demonstrated that RIS can provide performance 6Nn+7z<*&z  
superior to PMC when used as substrate for antennas. The RIS &U|c=$!\  
substrate is designed utilizing two-dimensional periodic printed
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metallic patches on a metal-backed high dielectric material. A J({D~
 
simplified circuit model describing the physical phenomenon of H#;*kc a4  
the periodic surface is developed for simple analysis and design `
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of the RIS substrate. Also a finite-difference time-domain (FDTD) x@rQ7K>  
full-wave analysis in conjunction with periodic boundary conditions , %z HykP  
and perfectly matched layer walls is applied to provide sV%DX5@  
comprehensive study and analysis of complex antennas on such Q9O_>mZy  
substrates. Examples of different planar antennas including dipole =N
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and patch antennas on RIS are considered, and their characteristics ~,1Sw7rE  
are compared with those obtained from the same antennas Po@;PR=  
over PEC and PMC. The simulations compare very well with !aF~5P7%  
measured results obtained from a prototype 10 miniaturized I]e+5 E0  
patch antenna fabricated on an RIS substrate. This antenna shows $B%KkD  
measured relative bandwidth, gain, and radiation efficiency of UiH7  
= 67%, = 45 dBi, and = 90%, respectively, Wmcd{MOS  
which constitutes the highest bandwidth, gain, and efficien .. +@3+WD  
j`RG Moq  

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