New Grammar

An updated grammar for NEC

The old grammar for NEC2 was designed with punch cards in mind. This has some problems. The most significant is that blank fields are difficult to specify, and defaults can sometimes be zeros, othertimes left out. In addition the parser, originally written in FORTRAN does not report good errors.

Two projects are under way. The files for these are in the antlr directory.

• A drop-in replacement parser for the existing card-based grammar. File nec.g
• New simulation language. File electro.g

Drop-in Replacement Parser

This is in beta development. The grammar is written in the [http://www.antlr.org/ ANTLR] language.

ELECTRO new simulation language

This is in very early stages. The language will allow C-style comments, and named arguments for the simulation functions. An example of the new language is below

g = geometry();
w0 = g.wire(start=[1,2,3], end=[2,3,4], r=0.01, n=5);
w1 = g.wire(start=w0.end,  end=[2,3,5], r=0.01, n=5);
g.arc(origin=[0,1,2], arc_radius=1.0, r=0.01 );
g.helix();
g.patch();
g.scale(3.0);
g.ground();

e = excitation(type=VOLTAGE, wire=w0, segment=3, freq=range(start=1.575GHz, end=1.675GHz, n=5));
e.extended_thin_wire_kernel = false; /* default */
    
execute();

theta = range(start=0.0, end=180, n=30);
phi = range(start=0.0, end=90, n=30);

/* Returns an array of radiation patterns */
radiation_pattern(mode="normal", theta=th, phi=ph);