Update magloop.html

magloop.html

@@ -69,7 +69,7 @@
             <div class="notes">
             <p style="text-align:center"><b><u><a href="./magloop_equations.html"> EQUATIONS USED </a></u></b></p>
             <b><u>Notes:</u></b><br>
-            The Magloop Antenna Calculator was developed to predict the characteristics of a small-loop (aka "magnetic loop" or "magloop")
+            The Magloop Antenna Calculator was developed to predict the characteristics of a small-transmitting-loop (aka "STL", "magnetic loop" or "magloop")
             antenna, given physical dimensions entered via slider widgets. <br>
             It supports:
             <ul>
@@ -100,7 +100,7 @@
             </ul>
             <u><b>Calculated parameters:</b></u>
             <ul>
-                <li>L : Inductance in microhenries.</li>
+                <li>L : Inductance in microhenries. Equations from [3].</li>
                 <li>A : Loop area in square meters or square feet.</li>
                 <li>C : Effective capacitance of the loop in picofarads.</li>
                 <li>peri : Perimeter of the main loop in meters or feet.</li>
@@ -133,6 +133,7 @@
             <b><u>References:</u></b><br>
             [1]: B. Austin, A. Boswell and M. Perks, <b>"Loss Mechanisms in the Electrically Small Loop Antenna"</b> <i>, IEEE Antennas and Propagation Magazine, 56, 4, August 2014, pp. 143.</i> <br>
             [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>
+            [3]: F W Grover, <b>"Formulas and Tables for the Calculation of the Inductance of Coils of Polygonal Form"</b> <i>Scientific Papers of the Bureau of Standards, Vol 18, p753</i> <br>
             <br>
             <b><u>Change history:</u></b><br>
             <b>[13-May-23] - V10.2</b> <br>
@@ -323,6 +324,9 @@
                 
                 const a_coil_radius = loop_diameter_meters * 0.5;
                 const coil_length = cond_diameter_meters * spacing_ratio * loop_turns;
+                const N = loop_turns; 
+                const l = (N>1) ? (coil_length * 100.0) : (cond_diameter_meters * 100.0); // coil length in cm
+
                 var retval = 0.0;
                 
                 if(shape == "circle") {
@@ -334,33 +338,30 @@
                     }
                 } else
                 if(shape == "octagon") {
-                    const N = loop_turns; 
                     const s = (100.0 * loop_diameter_meters) * 0.414213; // side length in cm
-                    const l = (N>1) ? (coil_length * 100.0) : (cond_diameter_meters * 100.0); // coil length in cm
-                    const bOn2r = l / (1.09868411*s);
-                    //retval = 1e-6 * 0.016 * (N**2) * s * ( Math.log((2.613*s*N)/((N+1)*l)) + 0.75143 + ((0.07153*(N+1)*l) / (s*N)));
-                    retval = 1e-6 * 0.016 * (N**2) * s * ( Math.log(1.0/bOn2r) + 0.75143 + 0.18693*bOn2r + 0.11969*bOn2r**2 - 0.08234*bOn2r**4);
+                    const bOn2r = l / (1.306563*s);
+                    //retval = 1e-6 * 0.016 * (N**2) * s * ( Math.log((2.613*s*N)/((N+1)*l)) + 0.75143 + ((0.07153*(N+1)*l) / (s*N)));  // ARRL Antennas Book 17th Ed
+                    retval = 1e-6 * 0.016 * (N**2) * s * ( Math.log(1.0/bOn2r) + 0.75143 + 0.18693*bOn2r + 0.11969*bOn2r**2 - 0.08234*bOn2r**4); // F W Grover p753
+                    //retval = 1e-6 * 0.016 * (N**2) * s * ( Math.log(s/l) + 1.711976 + 0.075143*(l/s) + 0.017528*(l/s)**2 - 0.001766*(l/s)**4);
                 } else
                 if(shape == "hexagon") {
-                    const N = loop_turns; 
                     const s = (100.0 * loop_diameter_meters) * 0.57735; // side length in cm
-                    const l = (N>1) ? (coil_length * 100.0) : (cond_diameter_meters * 100.0); // coil length in cm
                     const bOn2r = l / (loop_diameter_meters * 115.470);
-                    //retval = 1e-6 * 0.012 * (N**2) * s * ( Math.log((2.0*s*N)/((N+1)*l)) + 0.65533 + ((0.1348*(N+1)*l) / (s*N)));
-                    retval = 1e-6 * 0.012 * (N**2) * s * ( Math.log(1.0/bOn2r) + 0.65533 + 0.26960*bOn2r + 0.07736*bOn2r**2 - 0.05504*bOn2r**4);
+                    //retval = 1e-6 * 0.012 * (N**2) * s * ( Math.log((2.0*s*N)/((N+1)*l)) + 0.65533 + ((0.1348*(N+1)*l) / (s*N)));  // ARRL Antennas Book 17th Ed
+                    retval = 1e-6 * 0.012 * (N**2) * s * ( Math.log(1.0/bOn2r) + 0.65533 + 0.26960*bOn2r + 0.07736*bOn2r**2 - 0.05504*bOn2r**4); // F W Grover p753
                 } else
                 if(shape == "square") {
-                    const N = loop_turns; 
                     const s = (100.0 * loop_diameter_meters); // side length in cm
-                    const l = (N>1) ? (coil_length * 100.0) : (cond_diameter_meters * 100.0); // coil length in cm
                     const bOn2r = l / (loop_diameter_meters * 141.4214);
-                    //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);
+                    //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)));  // ARRL Antennas Book 17th Ed
+                    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); // F W Grover p753
                 }
+
                 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
             }
 

magloop_equations.html

@@ -17,13 +17,13 @@
         <i>[k_nagaoka - Nagaoka coefficient; l_coil - length of the coil in meters; r_loop - radius of the loop in meters]</i><br><br>
         <b>For octagonal loop antenna inductance:[F W Grover]</b><br>
         <img src="L_oct.png" alt="octagonal magloop antenna inductance"><br>
-        <i>[N - turns; s - section side length m; r - loop radius in m; b - coil length in m]</i><br><br>
+        <i>[L - microhenries; N - turns; s - section side length cm; r - loop circumradius in cm; b - coil length in cm]</i><br><br>
         <b>For hexagonal loop antenna inductance:[F W Grover]</b><br>
         <img src="L_hex.png" alt="hexagonal magloop antenna inductance"><br>
-        <i>[N - turns; s - section side length m; r - loop radius in m; b - coil length in m]</i><br><br>
+        <i>[L - microhenries; N - turns; s - section side length cm; r - loop circumradius in cm; b - coil length in cm]</i><br><br>
         <b>For square loop antenna inductance:[F W Grover]</b><br>
         <img src="L_sqr.png" alt="square magloop antenna inductance"><br>
-        <i>[N - turns; s - section side length m; r - loop radius in m; b - coil length in m]</i><br><br>
+        <i>[L - microhenries; N - turns; s - section side length cm; r - loop circumradius in cm; b - coil length in cm]</i><br><br>
         <b>Loss resistance:</b><br>
         <img src="MagloopLossResistance.png" alt="magloop multi-turn loss resistance"><br><br>
         <b>Surface resistance:</b><br>