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<!DOCTYPE HTML SYSTEM "html.dtd">
<HTML>
<HEAD>
<TITLE>Differences Between NEC-2, NEC-1, and AMP2 </TITLE></HEAD>
<BODY>
<H2></H2>
<CENTER>Differences Between NEC-2, NEC-1, and AMP2</CENTER>
<UL>
<LH><B>The following ar features of the NEC-1 code that differ from AMP2:</B></LH>
<LI>A new current expansion is used with continuous current and current
derivative along wires. The expansion enforces a new condition at multiple-wire
junctions and allows for current flowing onto the end cap at an open wire end</LI>
<LI>Where a wire connects to a surface, the surface-current expansion is
related to the current at the base of the wire rather than at the center of the
last wire segment.</LI>
<LI>An optional voltage source based on a discontinuity in current slope is
available.</LI>
<LI>In the thin-wire approximation, the current filament is on the wire axis
and the observation points are on the surface.</LI>
<LI>An optional extended thin-wire approximation is available.</LI>
<LI>Either a perfectly or imperfectly conducting ground may be used with
surface patches.</LI>
<LI>Either a perfect or imperfect ground may be used in incident plane wave.</LI>
<LI>Some constants have been changed including the velocity of light (2.998*10<SUP>8</SUP>m/sec.)
and the default frequency (299.8 MHz)</LI>
<LI>The wire-segment connection numbers have new meanings.
</LI>
<LI>The radiated field is the field at a range R multiplied by R with R
approaching infinity. In AMP and AMP2, the field is multiplied by R/lamda).
</LI>
<LI>Both near electric and magnetic fields may be computed. The NF card is no
longer used.
</LI>
<LI>Charge density may be printed for wires.
</LI>
<LI>The PT card is no longer cancelled by a new EX card.
</LI></UL>
<UL>
<LH><B>The following are features of NEC-2 that differ from NEC-1:</B></LH>
<LI>The NGF option has been added.
</LI>
<LI>The restart option has been removed.
</LI>
<LI>The Sommerfeld/Norton method has been added.
</LI>
<LI>Maximum coupling between antennas may be computed.
</LI>
<LI>wires may have tapered radius and segment lengths
</LI>
<LI>Patches may be specified as triangles, rectangles, or quadrangles.
</LI>
<LI>Rectangular surfaces with multiple patches may be specified.
</LI>
<LI>The SS card for surfaces has been eliminated.
</LI></UL>
<HR>
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