[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 cs-dvpMZ  
Antenna Miniaturization and Bandwidth Enhancement Using a Reactive Impedance Substrate @wTRoMHPQ  
Hossein Mosallaei, Senior Member, IEEE, and Kamal Sarabandi, Fellow, IEEE 2tMa4L%@C  
Abstract—The concept of a novel reactive impedance surface A4IPd  
(RIS) as a substrate for planar antennas, that can miniaturize WW3! ,ln_  
the size and significantly enhance both the bandwidth and the eFz!`a^dX  
radiation characteristics of an antenna is introduced. Using the xN>+!&3%w  
exact image formulation for the fields of elementary sources +*=?0\  
above impedance surfaces, it is shown that a purely reactive F!MxC  
impedance plane with a specific surface reactance can minimize Sd?+j;/"  
the interaction between the elementary source and its image in the (@3?JJ]1  
RIS substrate. An RIS can be tuned anywhere between perfectly qG8-UOUDt  
electric and magnetic conductor (PEC and PMC) surfaces offering Dy|DQ>?}  
a property to achieve the optimal bandwidth and miniaturization eCy]ugsi%  
factor. It is demonstrated that RIS can provide performance Uv|^k8(  
superior to PMC when used as substrate for antennas. The RIS ,/Yo1@U  
substrate is designed utilizing two-dimensional periodic printed ]%<0V,G q  
metallic patches on a metal-backed high dielectric material. A g7`uWAxZa  
simplified circuit model describing the physical phenomenon of p}MH LM  
the periodic surface is developed for simple analysis and design :}+m[g  
of the RIS substrate. Also a finite-difference time-domain (FDTD) 
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full-wave analysis in conjunction with periodic boundary conditions tKLAA+Z  
and perfectly matched layer walls is applied to provide LT:*K!>NOL  
comprehensive study and analysis of complex antennas on such f'&   
substrates. Examples of different planar antennas including dipole )A*Sl2ew  
and patch antennas on RIS are considered, and their characteristics z\6/?5D#
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are compared with those obtained from the same antennas N,?D<NjXl  
over PEC and PMC. The simulations compare very well with dY$jg  
measured results obtained from a prototype 10 miniaturized - *_"
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patch antenna fabricated on an RIS substrate. This antenna shows 9 :FzSD   
measured relative bandwidth, gain, and radiation efficiency of e*/ya8p?  
= 67%, = 45 dBi, and = 90%, respectively, vy{YGT  
which constitutes the highest bandwidth, gain, and efficien .. :qxd s>Xm  
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