NEC-LIST: Modeling of Simple Dipole

My name is Takahiro Tamae,and I have a question.

I calculated gain of Dipole antenna by two programs. One is modeling
an antenna by only one wire,but another is by three wires,as below.
As a result,I obtained different answers. The first's was 2.12dBi,the
other's was 4.24dBi. In addition,Impedances were 72.533+j3.471,
44.458+j1.389.

Could you tell me the reasons or my mistakes?

*****program1******
CM NEC-WIN Pro
CM Simple dipole antenna in Free Space
CM 1-Wire
CE
GW 1,9, 0,-48,0, 0,48,0, 0.1
GS 0 0 .01
GE 0
EX 0 1 5 0 1 0
FR 0 1 0 0 150 1
RP 0 181 1 1000 -90 90 1 1
FR 0 1 0 0 150 1
RP 0 181 1 1000 -90 0 1 1
EN

*****program2******
CM NEC-Win Pro
CM Simple dipole antenna in Free Space
CM 3-wires
CE
GW 1,4, 0,0.5,0, 0,48,0, 0.1
GW 2,4, 0,-0.5,0, 0,-48,0, 0.1
GW 3,1, 0,-0.5,0, 0,0.5,0, 0.1
GS 0 0 .01
GE 0
EX 0 3 1 00 1 0
FR 0 1 0 0 150 1
RP 0 181 1 1000 -90 90 1 1
FR 0 1 0 0 150 1
RP 0 181 1 1000 -90 0 1 1
EN

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Takahiro TAMAE
Telecom Research Lab,
Kyushu Matsushita Electric Co.,LTD.
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Received on Thu Oct 16 1997 - 10:29:07 EDT