Design of Compact Dual-Band Microstrip Patch Antenna

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  • Topic: Microstrip antenna, Polarization, Antenna
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Design of Compact Dual-Band Microstrip Patch Antenna
for GPSK-PCS Operation

Ho-yong Kim', Yong-nn Lee, Chung-ho Won, Hong-min Lcc Department of Electronics EngineeringKyon@ Univerrily hi-Dong, Yeongtong-Cu, Suwon-Si, Kyonggi-do, Korea email: hyounrsn@hotmail.com

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In recent years, with the advance o f technology, the demand for an antenna operating a1 mutibands i s increasing rapidly. Such as GPS and K-PCS, The multi-hand antennas with one feeding pon use the multiple resonance technolagy[l] such antennal are difficult lo provide a good polarization efficiency for GPS signal reception. So the integrated GPSIK-PCS dual-band antenna using two feeding pan has been proposed in this paper. Referenced dual-band antenna using two feeding pon has matched poiariration of integrated system.[2] but it has large size. Proposed antenna uses miniafurizalion technique that is to insect ilits. This technique is to increase elecVlcal surface length by slits.[3-5] Operating frequency o f proposed Bntenna is greatly lowered by slit^. Meander line patch and square ring patch with four diu o f proposed antenna are about 70% and 50% ofreferenced antenna size.

The proposed antenna composed of a low-profile cylindrical monopole with a top-loaded meander line patch for K-PCS Operation, and a comer-truncated square-ring microstrip patch antenna with four-slits for GPS ooeration.

Pmposed Antenna Design The geometry and design parameter of the proposed antenna for compact GPSIK-PCS operation i s presented in Figure I.The proposed antenna has the common ground plane, but i s

fed by separate feeding pon. The antenns for GPS-hand i s realized by using a corner-truncated square-ring microstrip patch with four slits. The outer side length and inner ride length are40mm(L,)and IZmm(&) ~ ~ p % t i d printed on a rubrtrale o f thickness 1.6mm(h) and y, relative peminiviry

(e, :4.4). The middle ofthe substrate is removed for inner rectangular d i t

area ( b x b ) of patch. Feed position for right-hand circularly polarized (RHCP) wave operation is placed along x-axis. and the distance of the probe feed away fram the patch center i s denoted as 6 . 6 m m ( / ) . The four-rlitr at the comers are of equal length I3.5mm(S)and

width Imm(w). Fig 2(a) shows simulated reNm loss of the proposed anlenna for GPS receiving antenna with various d i t lengths(S). It i s noted that the reSonant frequency rapidly lowered with increasingdesign parameter(S). In f h i ~ way, the excited surface current paths are lengthened in the propo~ed designs, and the operating frequency is greatly lowered.

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Also, the shorted meander line patch antenna with low-profile cylindrical monopole top is loaded at the center of square ring patch for K-PCS operation. For brbadband characteristic, cylindrical monopole has a large diameter of 6.2mm(d,) and l e n ~ h 10.7mm(h2). The

meander line patch has a ride lengh Z l m m ( p ) and is connected to the common ground by two same shorting posh, which have a diameter of 2.2mm(d2). By varying ofthe shorting ports

diameter(d2), good impedance matching can easily be obtained. Figure 2(b) shows simulated retum loss for the p r a p ~ ~ e d K-PCS antenna with various slit lengthr(m,) of meander line patch.

Meander line patch size can be reduced by increasing inserted slit length. Because of the antenna for K-PCS operation interfere the axial mtio of GPS receiving antenna, the miniatufimion of GPS antenna is limited. According to the experiment, the patch size of GPS antenna for circular polarized operation must he over about twice the size of KPCS antenna with meander line suunurc. In the proposed designs, the bandwidth of3-dB axial mtio is about 13 MHz, which is much larger than that required for GPS operation at 1575 MHz. The measured axial ratio ofthe antenna for GPS operation i s presented in Figure 3. Figure 4 shows measured re" 101 of proposed antenna. The...
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