fd2d_3.1.cpp

2D TM program FDTD fd2d_3.1.c

//fd2d_3.1.c   2D TM program

#include <math.h>
#include <stdio.h>
#include <stdlib.h>

#define IE 60
#define JE 60

main()
{
	float ga[IE][JE], dz[IE][JE], ez[IE][JE], hx[IE][JE], hy[IE][JE];
	int l, n, i, j, ic, jc, nsteps;
	float ddx, dt, T, epsz, pi, epsilon, sigma, eaf;
	float t0, spread, pulse;
	FILE *fp;

	ic=IE/2;
	jc=JE/2;
	ddx=0.01;
	dt=ddx/6e8;
	epsz=8.8e-12;
	pi=3.14159;

	for (j=0; j<JE; j++){
		printf("%2d  ",j);
		for (i=0;i<IE;i++){
			dz[i][j]=0.0;
			ez[i][j]=0.0;
			hx[i][j]=0.0;
			hy[i][j]=0.0;
			ga[i][j]=1.0;
			printf("%5.2f ", ga[i][j]);
		}
		printf("\n");
	}

	t0=30;
	spread=6.0;
	T=0;
	nsteps=1;

	while (nsteps>0){
		printf("nsteps --> "); 
		scanf("%d", &nsteps);
		for (n=1; n<=nsteps; n++){
			T=T+1;

			/* start of the Main loop */

			//calculate the Dz field
			for(j=1;j<JE;j++){
				for(i=1;i<IE;i++){
					dz[i][j]=dz[i][j]+0.5*(hy[i][j]-hy[i-1][j]-hx[i][j]+hx[i][j-1]);
				}
			}

			//put a Guassian pulse in thye middle
			pulse=exp(-0.5*pow( (t0-T)/spread,2.0 ) );
			dz[ic][jc]=pulse;

			//calculate the Ez field
			for(j=0;j<JE;j++){
				for(i=0;i<IE;i++){
					ez[i][j]=ga[i][j]*dz[i][j];
				}
			}

			//calculate the Hx field
			for(j=0; j<JE-1;j++){
				for(i=0;i<IE;i++){
					hx[i][j]=hx[i][j]+0.5*(ez[i][j]-ez[i][j+1]);
				}
			}
			//calculate the Hy field
			for(j=0; j<JE;j++){
				for(i=0;i<IE-1;i++){
					hy[i][j]=hy[i][j]+0.5*(ez[i+1][j]-ez[i][j]);
				}
			}
		}
	

	/*-----------End of the main FDTD loop-------------*/

	for(j=1;j<jc;j++){
		printf("%2d  ", j);
		for(i=1;i<ic;i++){
			printf("%5.2f ",ez[2*i][2*j]);
		}
		printf("\n");
	}

	//printf("T=%5.0f \n",T);

	/* write the E fireld to a file "Ez.xls" */
	fp=fopen("Ez.xls", "w");
	for(j=0;j<JE;j++){
		for(i=0;i<IE;i++){
			fprintf(fp, "%6.3f \t",ez[i][j]);
		}
		fprintf(fp,"\n");
	}
	fclose(fp);
	printf("T=%5.0f \n",T);
}

}