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Update to V8 - added parallel multi-loop (twin-arm) support

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miguel 2022-01-13 23:48:17 +11:00
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magloop.html
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@ -7,7 +7,7 @@
<link rel="stylesheet" href="magloop.css">
</head>
<body>
<header>Miguel <a href="mailto:vk3cpu@gmail.com">VK3CPU</a> - Magloop Antenna Calculator V7</header>
<header>Miguel <a href="mailto:vk3cpu@gmail.com">VK3CPU</a> - Magloop Antenna Calculator V8</header>
<section class="gridLayoutClass">
<div class="chart-container" style="position: relative;">
<canvas id="chartCanvas" class="chartCanvasClass">
@ -25,7 +25,7 @@
</div>
<div class="sliders">
<label for="loop_turns_slider">N:</label>
<input type="range" id="loop_turns_slider" min="1" max="8" value="1.0" step="1.0">
<input type="range" id="loop_turns_slider" min="0" max="8" value="1.0" step="1.0">
</div>
<div class="sliders">
<label for="loop_spacing_slider">c/a:</label>
@ -85,7 +85,7 @@
<ul>
<li>&#8960a : Conductor diameter in millimeters (mm) or inches ("). (Measured between opposing conductor outer surfaces.)</li>
<li>&#8960b : Loop diameter in meters (m) or feet ('). (Measured between the conductor centers.)</li>
<li>N : Number of turns or loops.</li>
<li>N : Number of turns or loops. Sweeping left-to-right for parallel multiloop, then single loop, then series multiloop configurations. A "(P)" indicates a multiloop antenna configured with parallel main loops.</li>
<li>c/a : is the spacing ratio; based on 'c' being the inter-winding spacing for multi-turn loops measured between conductor centers, and 'a' is the conductor diameter. (Must be >= 1.1)
A low-value will increase the resistance due to the proximity effect. (Ignore for single-turn loops.)</li>
<li>Tx : The transmit power in Watts. This affects the predicted voltage across the capacitor (Vcap), and the RMS loop current (Ia).</li>
@ -126,6 +126,8 @@
[2]: A. Boswell, A. J. Tyler and A. White, <b>"Performance of a Small Loop Antenna in the 3 - 10 MHz Band"</b> <i>, IEEE Antennas and Propagation Magazine, 47, 2, April 2005, pp. 5 1 -56.</i> <br>
<br>
<b><u>Change history:</u></b><br>
<b>[13-Jan-22] - V8</b> <br>
* Added support for parallel conductor magloop antennas.<br>
<b>[21-Nov-21] - V7</b> <br>
* Upgrade Chart.js to the latest version, v3.5.1.<br>
* Tooltips are now justified, (using monospace fonts) and support changing metric prefix.<br>
@ -190,6 +192,8 @@
var units = "metric";
var conductivity = 58e6; // Default is annealed copper
var shape = "circle"; // Shape of the main loop
var loop_turns = 1; //
var loop_mode = "series"; // Series or parallel. When loop_turns_slider.value == 0, loop_turns is 2 and loop_mode is "parallel"
var inductance = 0.0;
var area = 0.0; // Loop area in square meters.
@ -199,7 +203,7 @@
var conductor_length = 0.0; // Total conductor length
var R_ext = 0.0; // External losses due to capacitor resistance and ground effects, in ohms
var metal = "Cu"; // Default metal is copper
const proximityResistance = {
// From G. S. Smith, "Radiation Efficiency of Electrically Small Multiturn Loop Antennas", IEEE Trans Antennas Propagation, September 1972
// 0 - this is the corresponding x-axis value. 1 - single loop adds zero to proximity resistance. Others measured empirically.
@ -232,12 +236,14 @@
}
function setGlobals() {
loop_turns = loop_turns_slider.value >= 1 ? loop_turns_slider.value : 2;
loop_mode = loop_turns_slider.value >= 1 ? "series" : "parallel";
inductance = getInductance();
area = getArea();
perimeter = getPerimeter();
loop_capacitance = (loop_turns_slider.value > 1) ? multiloopCapacitance() : (2.69e-12 * perimeter);
loop_capacitance = ((loop_turns > 1) && (loop_mode == "series")) ? multiloopCapacitance() : (2.69e-12 * perimeter);
srf = calculateSRF();
conductor_length = ((((perimeter* loop_turns_slider.value) ** 2.0) + ((loop_spacing_slider.value * conductor_diameter_slider.value * 1e-3 * loop_turns_slider.value) ** 2.0)) ** 0.5);
conductor_length = ((((perimeter* loop_turns) ** 2.0) + ((loop_spacing_slider.value * conductor_diameter_slider.value * 1e-3 * loop_turns) ** 2.0)) ** 0.5);
R_ext = external_losses_slider.value * 0.001;
}
@ -290,7 +296,6 @@
const loop_diameter_meters = loop_diameter_slider.value;
const cond_diameter_meters = conductor_diameter_slider.value * 1e-3;
const spacing_ratio = loop_spacing_slider.value;
const loop_turns = loop_turns_slider.value;
const a_coil_radius = loop_diameter_meters * 0.5;
const coil_length = cond_diameter_meters * spacing_ratio * loop_turns;
@ -328,20 +333,26 @@
//retval = 1e-6 * 0.008 * (N**2) * s * ( Math.log((1.4142*s*N)/((N+1)*l)) + 0.37942 + ((0.3333*(N+1)*l)/(s*N)));
retval = 1e-6 * 0.008 * (N**2) * s * ( Math.log(1.0/bOn2r) + 0.37942 + 0.47140*bOn2r - 0.014298*bOn2r**2 - 0.02904*bOn2r**4);
}
if(loop_mode == "parallel") {
// then N==2, so divide by 4 to go from serial to parallel inductance:
retval *= 0.25;
}
return retval; // In Henries
}
function radiationResistance(frequency) {
const n_turns = loop_turns_slider.value;
const wavelength = 3e8 / frequency;
var retval = 0.0;
if(shape == "circle") {
const k = 20.0 * (Math.PI ** 2.0);
const l = (Math.PI * loop_diameter_slider.value) / wavelength;
retval = (n_turns ** 2.0) * k * (l ** 4.0);
retval = (loop_turns ** 2.0) * k * (l ** 4.0);
} else {
retval = (31171.0 * n_turns**2.0 * area**2.0) / (wavelength**4.0);
retval = (31171.0 * loop_turns**2.0 * area**2.0) / (wavelength**4.0);
}
if(loop_mode == "parallel") {
retval *= 0.25;
}
return retval;
}
@ -372,17 +383,14 @@
function nagaokaCoefficient() {
// From Knight's 2016 paper on coil self-resonance, attributed to Wheeler's 1982 eqn as modified by Bob Weaver
var retval;
const c_spacing = 1e-3 * loop_spacing_slider.value * conductor_diameter_slider.value;
const x = loop_diameter_slider.value / (c_spacing * loop_turns_slider.value);
const x = loop_diameter_slider.value / (c_spacing * loop_turns);
const zk = 2.0 / (Math.PI * x);
const k0 = 1.0 / (Math.log(8.0 / Math.PI) - 0.5);
const k2 = 24.0 / (3.0 * Math.PI**2 - 16.0);
const w = -0.47 / (0.755 + x)**1.44;
const p = k0 + 3.437/x + k2/x**2 + w;
retval = zk * (Math.log(1 + 1/zk) + 1/p);
//console.log(retval);
return retval;
return zk * (Math.log(1 + 1/zk) + 1/p);
}
function ctdw(ff, ei, ex) {
@ -403,7 +411,7 @@
const h = 1e-3 * loop_spacing_slider.value * conductor_diameter_slider.value;
const ei = 1.0; // Assume internal epsilon is air (or free-space)
const ex = 1.0; // Assume external epsilon is air (or free-space)
const solenoid_length = loop_turns_slider.value * h;
const solenoid_length = loop_turns * h;
const ff = solenoid_length / loop_diameter_slider.value;
// How much longer is the perimeter compared to the circumference if it were circular:
@ -438,13 +446,12 @@
function getProximityResFromSpacing(spacing_ratio) {
// Use the proximityResistance look-up table and interpolate values depending on the spacing ratio and the number of turns.
var retval = 0.0;
var n_turns = 1 * loop_turns_slider.value;
var i = 0;
for (i = 0; i < (proximityResistance[0].length-1); i++) {
if(spacing_ratio <= proximityResistance[0][i+1]) {
// Linear interpolation between empirical proximity resistance values:
retval = (((spacing_ratio - proximityResistance[0][i]) / (proximityResistance[0][i+1] - proximityResistance[0][i])
* (proximityResistance[n_turns][i+1] - proximityResistance[n_turns][i])) + proximityResistance[n_turns][i]);
* (proximityResistance[loop_turns][i+1] - proximityResistance[loop_turns][i])) + proximityResistance[loop_turns][i]);
break;
}
}
@ -455,18 +462,20 @@
// Frequency in Hertz
const a_coil_radius = loop_diameter_slider.value * 0.5;
const b_conductor_radius = conductor_diameter_slider.value * 0.0005;
const n_turns = loop_turns_slider.value;
const loop_spacing_ratio = loop_spacing_slider.value;
const mu0 = 4.0 * Math.PI * 1e-7;
// How much longer is the perimeter compared to the circumference if it were circular:
const shape_factor = perimeter / (Math.PI * loop_diameter_slider.value);
const k = (n_turns * a_coil_radius / b_conductor_radius);
const k = (loop_turns * a_coil_radius / b_conductor_radius);
const Rp = getProximityResFromSpacing(loop_spacing_ratio);
const Rs = Math.sqrt(Math.PI * frequency * mu0 / conductivity);
//const R0 = (n_turns * Rs) / (2.0 * Math.PI * b_conductor_radius);
const R_ohmic = shape_factor * k * Rs * (Rp + 1.0);
//const R0 = (loop_turns * Rs) / (2.0 * Math.PI * b_conductor_radius);
var R_ohmic = shape_factor * k * Rs * (Rp + 1.0);
if(loop_mode == "parallel") {
R_ohmic *= 0.25;
}
//const R_ohmic = k * Rs * (Rp / R0 + 1.0);
return R_ohmic;
}
@ -486,8 +495,6 @@
const R_ohmic = lossResistance(freq * 1e6);
const R_rad = radiationResistance(freq * 1e6);
const efficiency = 100.0 * R_rad / (R_rad + R_ohmic + R_ext);
//const efficiency = 100.0 / (1.0 + (R_ohmic / R_rad));
//const efficiency = 10.0 * Math.log10(1.0 / (1.0 + (R_ohmic / R_rad))); // for Efficiency in dB
retval.push({x:freq, y:efficiency});
});
return retval;
@ -848,7 +855,7 @@
setGlobals();
drawFrontDesign();
drawSideDesign();
if(loop_turns_slider.value > 1) {
if(loop_turns > 1) {
updateFrequencies();
}
myChart.data.datasets[0].data = calculateTuningCapacitor();
@ -1354,48 +1361,76 @@
const cond_radius = conductor_diameter_slider.value / 12;
const cond_spacing = 2 * cond_radius * loop_spacing_slider.value;
const start_x = win_width/2 - loop_turns_slider.value * cond_spacing * 0.5;
const start_x = (loop_turns > 0) ? win_width/2 - loop_turns * cond_spacing * 0.5 : win_width/2;
const top_y = win_height * 0.2;
const bot_y = win_height * 0.7;
for (let i = 0; i < loop_turns_slider.value; i++) {
sctx.beginPath();
sctx.arc(start_x + i * cond_spacing, bot_y, cond_radius, 0, Math.PI);
sctx.arc(start_x + cond_spacing * 0.5 + i * cond_spacing, top_y, cond_radius, Math.PI, 0);
sctx.lineTo(start_x + i * cond_spacing + cond_radius, bot_y);
sctx.fill();
if(loop_mode == "series") {
if(loop_turns > 1) {
for (let i = 0; i < loop_turns; i++) {
sctx.beginPath();
sctx.arc(start_x + i * cond_spacing, top_y, cond_radius, Math.PI, 0);
sctx.arc(start_x + cond_spacing * 0.5 + i * cond_spacing, bot_y, cond_radius, 0, Math.PI);
//sctx.lineTo(start_x + i * cond_spacing + cond_radius, top_y);
sctx.fill();
sctx.beginPath();
sctx.moveTo(start_x + cond_spacing * 0.5 + i * cond_spacing + cond_radius, top_y);
sctx.lineTo(start_x + (i+1) * cond_spacing + cond_radius, bot_y);
sctx.arc(start_x + (i+1) * cond_spacing, bot_y, cond_radius, 0, Math.PI, false);
sctx.lineTo(start_x + cond_spacing * 0.5 + i * cond_spacing - cond_radius, top_y);
sctx.stroke();
sctx.beginPath();
sctx.moveTo(start_x + cond_spacing * 0.5 + i * cond_spacing + cond_radius, bot_y);
sctx.lineTo(start_x + (i+1) * cond_spacing + cond_radius, top_y);
sctx.arc(start_x + (i+1) * cond_spacing, top_y, cond_radius, 0, Math.PI, true);
sctx.lineTo(start_x + cond_spacing * 0.5 + i * cond_spacing - cond_radius, bot_y);
sctx.stroke();
}
} else {
sctx.beginPath();
sctx.arc(start_x + cond_spacing, bot_y, cond_radius, 0, Math.PI);
sctx.arc(start_x + cond_spacing, top_y, cond_radius, Math.PI, 0);
sctx.lineTo(start_x + cond_spacing + cond_radius, bot_y);
sctx.fill();
}
} else {
// "parallel" - means draw a two-arm parallel magloop:
sctx.beginPath();
sctx.arc(start_x + 0.5 * cond_spacing, bot_y, cond_radius, 0, Math.PI);
sctx.arc(start_x + 0.5 * cond_spacing, top_y, cond_radius, Math.PI, 0);
sctx.lineTo(start_x + 0.5 * cond_spacing + cond_radius, bot_y);
sctx.fill();
sctx.beginPath();
sctx.arc(start_x + 1.5 * cond_spacing, bot_y, cond_radius, 0, Math.PI);
sctx.arc(start_x + 1.5 * cond_spacing, top_y, cond_radius, Math.PI, 0);
sctx.lineTo(start_x + 1.5 * cond_spacing + cond_radius, bot_y);
sctx.fill();
}
// Draw left spacing arrow:
const dim_y = win_height * 0.8;
sctx.beginPath();
sctx.moveTo(start_x - 20, dim_y);
sctx.lineTo(start_x, dim_y);
sctx.lineTo(start_x - 7, dim_y + 7)
sctx.lineTo(start_x - 7, dim_y - 7)
sctx.lineTo(start_x, dim_y);
sctx.moveTo(start_x, dim_y - 7);
sctx.lineTo(start_x, dim_y + 7);
sctx.stroke();
// Draw right spacing arrow:
sctx.beginPath();
sctx.moveTo(start_x + cond_spacing + 20, dim_y);
sctx.lineTo(start_x + cond_spacing, dim_y);
sctx.lineTo(start_x + cond_spacing + 7, dim_y + 7)
sctx.lineTo(start_x + cond_spacing + 7, dim_y - 7)
sctx.lineTo(start_x + cond_spacing, dim_y);
sctx.moveTo(start_x + cond_spacing, dim_y - 7);
sctx.lineTo(start_x + cond_spacing, dim_y + 7);
sctx.stroke();
if(loop_turns > 1) {
sctx.beginPath();
//sctx.moveTo(0.5 * win_width - 0.5 * cond_spacing + shift - 20, dim_y);
sctx.moveTo(start_x + 0.5 * cond_spacing - 20, dim_y);
sctx.lineTo(start_x + 0.5 * cond_spacing , dim_y);
sctx.lineTo(start_x + 0.5 * cond_spacing - 7, dim_y + 7)
sctx.lineTo(start_x + 0.5 * cond_spacing - 7, dim_y - 7)
sctx.lineTo(start_x + 0.5 * cond_spacing , dim_y);
sctx.moveTo(start_x + 0.5 * cond_spacing , dim_y - 7);
sctx.lineTo(start_x + 0.5 * cond_spacing , dim_y + 7);
sctx.stroke();
// Draw right spacing arrow:
sctx.beginPath();
sctx.moveTo(start_x + 1.5 * cond_spacing + 20, dim_y);
sctx.lineTo(start_x + 1.5 * cond_spacing , dim_y);
sctx.lineTo(start_x + 1.5 * cond_spacing + 7, dim_y + 7)
sctx.lineTo(start_x + 1.5 * cond_spacing + 7, dim_y - 7)
sctx.lineTo(start_x + 1.5 * cond_spacing , dim_y);
sctx.moveTo(start_x + 1.5 * cond_spacing , dim_y - 7);
sctx.lineTo(start_x + 1.5 * cond_spacing , dim_y + 7);
sctx.stroke();
}
sctx.textAlign = "left";
sctx.font = turns_font;
sctx.fillText("N = " + loop_turns_slider.value.toString(), 8, win_height * 0.1 + 3);
sctx.fillText("N = " + loop_turns.toString() + ((loop_mode == "series") ? "" : " (P)"), 8, win_height * 0.1 + 3);
sctx.font = spacing_font;
sctx.fillText("c/a = ", 8, win_height * 0.1 + 18);
sctx.fillText((loop_spacing_slider.value*1.0).toPrecision(3).toString(), 8, win_height * 0.1 + 33);
@ -1417,12 +1452,14 @@
}
// Draw spacing text:
sctx.textAlign = "center";
const spc = (loop_turns_slider.value > 1) ? loop_spacing_slider.value * conductor_diameter_slider.value : 0.0;
if(units == "metric") {
sctx.fillText("c = " + spc.toPrecision(3).toString() + " mm", start_x + cond_spacing, dim_y + 20);
} else {
sctx.fillText("c = " + (spc/25.4).toPrecision(3).toString() + " in", start_x + cond_spacing, dim_y + 20);
if(loop_turns > 1) {
sctx.textAlign = "center";
const spc = (loop_turns > 1) ? loop_spacing_slider.value * conductor_diameter_slider.value : 0.0;
if(units == "metric") {
sctx.fillText("c = " + spc.toPrecision(3).toString() + " mm", start_x + cond_spacing, dim_y + 20);
} else {
sctx.fillText("c = " + (spc/25.4).toPrecision(3).toString() + " in", start_x + cond_spacing, dim_y + 20);
}
}
}