kopia lustrzana https://github.com/miguelvaca/vk3cpu
Create antenna.html
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<!DOCTYPE html>
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<html lang="en">
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<!-- @file : antenna.html -->
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<!-- @author : J Miguel Vaca -->
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<!-- @remark : This webpage uses Computational Electromagnetics (CEM) to solve antenna currents and fields. It then uses WebGL to visualise the currents -->
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<!-- : and fields produced by the antenna. -->
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<!-- : Idea - allow adding wire antennas, one-at-a-time. Then have controls at the ends to move ends, stretch or shring the wire. -->
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<!-- Have a control in the middle that can be used to reposition the camera. Also a control to move the feedpoint along the wire. -->
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<!-- Support multiple feedpoints, but with a single master feed (or frequency), and the others are slaved off the master, but with a controllable phase -->
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<!-- shift that will allow modelling of phased-arrays. -->
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<head>
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<title>VK3CPU Antenna</title>
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<meta charset="utf-8">
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<meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
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<!--link type="text/css" href="css/base.css" rel="stylesheet"/-->
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<!--link type="text/css" href="css/visualisation.css" rel="stylesheet"/-->
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</head>
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<body>
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<div id="info">
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Visualisation by : <a href="mailto:vacamiguel@gmail.com">J Miguel Vaca</a>
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</div>
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<!-- math.js library scripts -->
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<script src="https://cdnjs.cloudflare.com/ajax/libs/mathjs/7.5.1/math.min.js"></script>
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<script src="https://threejs.org/build/three.js"></script>
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<!--script src="./dat.gui.min.js"></script-->
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<script src="https://threejs.org/examples/js/controls/OrbitControls.js"></script>
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<script>
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var container; //, stats;
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var camera, scene, renderer, geometry, controls;
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var clock = new THREE.Clock();
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var tick = 0;
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function Antennas() {
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//
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this.wire = [];
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this.antenna_types = {
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'order' : ['dipole_v'],
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'antennas' : {
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'dipole_v' : {
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'wires' : [
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[[0.00,-0.35, 0.00], [0.00, 0.35, 0.00]]
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],
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},
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'dipole_h' : {
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'wires' : [
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[[0.00, 0.00, -0.35], [0.00, 0.00, 0.35]]
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],
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},
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'yagi_h' : {
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'wires' : [
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[[-0.25, 0.00, -0.35], [-0.25, 0.00, 0.35]], // Reflector
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[[0.00, 0.00, -0.25], [0.00, 0.00, 0.25]], // Exciter
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[[0.25, 0.00, -0.25], [0.25, 0.00, 0.25]], // Director
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[[0.50, 0.00, -0.25], [0.50, 0.00, 0.25]], // Director
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[[0.75, 0.00, -0.25], [0.75, 0.00, 0.25]]// Director
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],
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}
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},
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};
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//
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this.getThreeObject3D = function () {
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const material = new THREE.LineBasicMaterial({color:0xffff00});
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const points = [];
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const scale_factor = 100.0;
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var wires = this.antenna_types['antennas']['yagi_h']['wires'];
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wires.forEach(element => {
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points.push(new THREE.Vector3(element[0][0] * scale_factor, element[0][1] * scale_factor, element[0][2] * scale_factor));
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points.push(new THREE.Vector3(element[1][0] * scale_factor, element[1][1] * scale_factor, element[1][2] * scale_factor));
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});
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const geometry = new THREE.BufferGeometry().setFromPoints(points);
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return new THREE.LineSegments( geometry, material );
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};
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}
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function Antenna() {
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const material = new THREE.LineBasicMaterial({color:0x00ff00});
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const points = [];
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points.push(new THREE.Vector3(0.0, 0.0, 0.0));
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points.push(new THREE.Vector3(0.0, 100.0, 0.0));
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points.push(new THREE.Vector3(0.0, 0.0, 10.0));
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const geometry = new THREE.BufferGeometry().setFromPoints(points);
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return new THREE.Line( geometry, material );
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}
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init();
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animate();
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function init() {
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container = document.createElement( 'div' );
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document.body.appendChild( container );
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camera = new THREE.PerspectiveCamera( 75, window.innerWidth / window.innerHeight, 5, 15000 );
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camera.position.y = 120;
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camera.position.z = 400;
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scene = new THREE.Scene();
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scene.background = new THREE.Color(0.0, 0.0, 0.0);
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//renderer = new THREE.WebGLRenderer({antialias:true});
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renderer = new THREE.WebGLRenderer({antialias:true});
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renderer.setPixelRatio( window.devicePixelRatio );
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renderer.setSize( window.innerWidth, window.innerHeight );
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container.appendChild( renderer.domElement );
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controls = new THREE.OrbitControls( camera, renderer.domElement );
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//stats = new Stats();
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//container.appendChild( stats.dom );
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window.addEventListener( 'resize', onWindowResize, false );
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// Add an axis:
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var axis = new THREE.AxesHelper(200);
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scene.add(axis);
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// Create a half-wavelength long wire, with a radius of 0.001 lambda, and segmented into 10 pieces:
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wire = createWire(0.5, 0.0001, 45);
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//console.log(wire);
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//console.log(wire);
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frequency = 3e8;
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// Solve the z-matrix:
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var impedance = calculateZMatrix(wire);
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console.log(impedance[22][22]);
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var admittance = math.inv(impedance);
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//console.log(admittance);
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var V = createVoltageVector(45);
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var I = math.multiply(admittance, V);
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console.log(I[23]);
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V = math.multiply(impedance, I);
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var ant = new Antennas();
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scene.add(ant.getThreeObject3D());
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}
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function createWire(length, wire_radius, segments) {
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// dimensions in lambda
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var wire = {};
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wire.length = length;
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wire.seg_len = length / segments;
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wire.radius = wire_radius;
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const offset = 0.5 * length;
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wire.points = [];
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wire.points.push([0.0, 0.0, -offset]);
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for (let i = 0; i < segments; i++) {
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wire.points.push([0.0, 0.0, i * wire.seg_len + 0.5 * wire.seg_len - offset]);
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wire.points.push([0.0, 0.0, (i+1) * wire.seg_len - offset]);
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}
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return wire;
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}
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function psi(wire, n, m) {
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var retval = 0.0;
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const k = 2.0 * Math.PI; // Normalised wavelength is equal to 1.0 - otherwise 2*pi/wavelength
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const fourPI = 4.0 * Math.PI;
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var Rmn = 0.0;
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// From MININEC thesis (3-36) and (3-37):
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if(m==n) {
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retval = math.complex((1.0/(2.0*Math.PI*wire.seg_len)) * Math.log(wire.seg_len / wire.radius), (-k/fourPI));
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} else {
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Rmn = Math.sqrt((wire.points[m][0] - wire.points[n][0])**2 + (wire.points[m][1] - wire.points[n][1])**2 + (wire.points[m][2] - wire.points[n][2])**2);
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retval = math.multiply(math.complex(Math.cos(k * Rmn), -Math.sin(k * Rmn)), (1/(fourPI*Rmn)));
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}
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//console.log(n, m, retval);
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return retval;
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}
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function psi_old(wire, n, m) {
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var retval = 0.0;
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const k = 2.0 * Math.PI; // Normalised wavelength is equal to 1.0 - otherwise 2*pi/wavelength
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const fourPI = 4.0 * Math.PI;
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var Rmn = 0.0;
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// From MININEC thesis (3-36) and (3-37):
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if(m==n) {
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Rmn = Math.sqrt(wire.radius**2 + (wire.seg_len*0.5)**2);
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} else {
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Rmn = Math.sqrt((wire.points[m][0] - wire.points[n][0])**2 + (wire.points[m][1] - wire.points[n][1])**2 + (wire.points[m][2] - wire.points[n][2])**2);
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}
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retval = math.multiply(math.complex(Math.cos(k * Rmn), -Math.sin(k * Rmn)), (1/(fourPI*Rmn)));
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//console.log(n, m, retval);
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return retval;
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}
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// Use Harrington's equations (129) and (135):
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function psi2(wire, n, m) {
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var retval = 0.0;
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var Rmn = 0.0;
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// Calculate the range from the source point (n) to the observation point (m) depending whether it is the same segment or not:
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if(m==n) {
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Rmn = Math.sqrt(wire.radius**2 + (wire.seg_len*0.5)**2);
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} else {
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Rmn = Math.sqrt((wire.points[m][0] - wire.points[n][0])**2 + (wire.points[m][1] - wire.points[n][1])**2 + (wire.points[m][2] - wire.points[n][2])**2);
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}
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// Now if r<10a, use 129. If r>=10a, use 135:
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const alpha = wire.seg_len*0.5;
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const zeta = wire.points[m][2] - wire.points[n][2]; // This is z at m when n is set as the coordinate space origin. So need to transform coord-space to make it N-centric first! Uugh!
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// zeta is the projection of m onto the n segment, if the n-segment were centered at the origin along the z-direction.
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const mn = math.subtract(wire.points[m], wire.points[n-1])
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//var zeta = math.dot(wire.points[m], wire.points[n]);
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//zeta = zeta / ()
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const rho = 0;
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if(Rmn < (10.0 * alpha)) {
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// Eq 129:
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var t1 = math.complex(Math.cos(k * Rmn), -Math.sin(k * Rmn));
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t1 = math.multiply((1.0/(8.0*Math.PI*alpha)), t1);
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const i1 = Math.log((zeta + alpha + Math.sqrt(rho**2 + (zeta + alpha)**2)) / (zeta - alpha + Math.sqrt(rho**2 + (zeta - alpha)**2)));
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const i2 = 2 * alpha;
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const i3 = (0.5 * (alpha + zeta)) * Math.sqrt(rho**2 + (alpha + zeta)**2) + (0.5 * (alpha - zeta)) * Math.sqrt(rho**2 + (zeta - alpha)**2) + (0.5 * rho**2 * i1);
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const i4 = (2*alpha*rho**2) + (0.333333 * (2*alpha**3 + 6*alpha*zeta**2));
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const re = i1 - 0.5*k**2 * (i3 - 2*Rmn*i2 + Rmn**2*i1);
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const im = -k*(i2 - Rmn*i1) + (1.0/6)*k**3*(i4 - 3*Rmn*i3 + 3*Rmn**2*i2 - Rmn**3*i1);
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retval = math.complex(math.multiply(t1, re), math.multiply(t1, im));
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} else {
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// Eq 135:
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}
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return retval;
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}
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function calculateZMatrix(wire) {
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const w = 2.0 * Math.PI * frequency;
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const k = 2.0 * Math.PI * frequency / 3e8; // 2*pi/lambda
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const e0 = 8.854187e-12;
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const mu0 = 4.0 * Math.PI * 1e-7;
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const fourPI = 4.0 * Math.PI;
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var Z = [];
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for (let m = 1; m < wire.points.length; m+=2) {
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var row = [];
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for (let n = 1; n < wire.points.length; n+=2) {
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// Use Harrington's method:
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var tmp = math.dot(math.subtract(wire.points[n+1], wire.points[n-1]), math.subtract(wire.points[m+1], wire.points[m-1]));
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tmp *= w * mu0;
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tmp = math.multiply(math.complex(0,tmp), psi(wire, n, m));
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var tmp2 = math.add(psi(wire, n+1, m+1), psi(wire, n-1, m-1));
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var tmp3 = math.add(psi(wire, n-1, m+1), psi(wire, n+1, m-1));
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var tmp4 = math.subtract(tmp2, tmp3);
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tmp2 = math.multiply(tmp4, math.complex(0,-1/(w*e0)));
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row.push(math.add(tmp, tmp2));
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}
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Z.push(row);
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}
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return Z;
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}
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function createVoltageVector(segments) {
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var retval = [];
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for(var i=0; i<segments; i++){
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if(i == 22) {
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retval.push(math.complex(1,0));
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} else {
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retval.push(math.complex(0,0));
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}
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}
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return retval;
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}
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function calculateVoltage() {
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var retval = [];
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var x_axis = 0.0;
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for(var i=0; i<V.length; i++) {
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x_axis += wire.seg_len;
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retval.push({x:x_axis, y:V[i].toPolar().r});
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}
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return retval;
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}
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function calculateCurrent() {
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var retval = [];
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var x_axis = 0.0;
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for(var i=0; i<I.length; i++) {
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x_axis += wire.seg_len;
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retval.push({x:x_axis, y:I[i].toPolar().r});
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}
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return retval;
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}
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function onWindowResize() {
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camera.aspect = window.innerWidth / window.innerHeight;
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camera.updateProjectionMatrix();
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renderer.setSize( window.innerWidth, window.innerHeight );
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// TODO - need to notify scene object shaders (via uniforms) here if required!
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// becvfUniforms.cameraConstant.value = getCameraConstant( camera );
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}
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function getCameraConstant( camera ) {
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return window.innerHeight / ( Math.tan( THREE.Math.DEG2RAD * 0.5 * camera.fov ) / camera.zoom );
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}
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function animate() {
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// Update the elapsed time to later provide to the shaders:
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var delta = clock.getDelta();
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tick += delta;
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if ( tick < 0 ) tick = 0;
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// Tell WebGL to call the 'animate()' function for the next screen refresh:
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requestAnimationFrame( animate );
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// Render the scene, and update the stats:
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renderer.render( scene, camera );
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//stats.update();
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}
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</script>
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</body>
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</html>
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Reference in New Issue