<html>
<head>
<title>Two Element Quad Calculator</title>
</head>
<body bgcolor=#000088 text=#ffcc00 link=#ffcc00 alink=#ff6600 vlink=#dd9900>
Program to calculate the dimensions of a resonant square 2-element quad
beam.<br>
<br>
All equations calibrated to NEC antenna modeling software for wire
diameters from 3.16e-5 to 1e-2 wavelengths within about 0.5% from 3.5 to 250
MHz.<br>
<br>
Original BASIC program by L.B. Cebik W4RNL<br>
<a href="2elequad.phps">PHP4</a> port by Rich Alloway N3WWN<br>
<br>
<form action="<?=$_SERVER['PHP_SELF']?>" method=post>
<?php
if( $_SERVER["REQUEST_METHOD"] == "POST" ) {
$f = $_REQUEST['f'];
$wd = $_REQUEST['wd'];
$u = $_REQUEST['u'];
}
?>
Frequency: <input type=text name=f value=<?=$f?>> MHz<br>
Wire Diameter: <input type=text name=wd value=<?=$wd?>>
<span style="color: #000000">
<select name=u>
<option value=1 <?php if( $u == 1) print "SELECTED";?>>Inches
<option value=2 <?php if( $u == 2) print "SELECTED";?>>Millimeters
<option value=3 <?php if( $u == 3) print "SELECTED";?>>Wavelengths
</select><br>
<input type=submit><input type=reset>
</span>
</form>
<?php
if( isset( $f )) {
if( $u == 1 ) {
$wli = 11802.71 / $f;
$d = $wd / $wli;
}
if( $u == 2 ) {
$wli = 299792.5 / $f;
$d = $wd / $wli;
}
if( $u == 3 ) {
$d = $wd;
}
print "Wire Diameter in Wavelenghts: $d<br><br>";
$d1 = log10( $d );
if( $d1 < -4.5 )
print "Wire diameter less than 3e-5 wavelengths: results uncertain!<br><br>";
if( $d1 > -2 )
print "Wire diameter greater than 1e-2 wavelengths: results uncertain!<br><br>";
$ad = 0.00336;
$bd = 0.04966518519;
$cd = 0.2731955556;
$dd = 0.6716364021;
$ed = 1.644147937;
$de = ($ad * pow($d1,4)) + ($bd * pow($d1,3)) + ($cd * pow($d1,2)) + ($dd * $d1) + $ed;
$ar = 0.003173333333;
$br = 0.0508237037;
$cr = 0.3081977778;
$dr = 0.8663851852;
$er = 2.040064444;
$re = ($ar * pow($d1,4)) + ($br * pow($d1,3)) + ($cr * pow($d1,2)) + ($dr * $d1) + $er;
$as = -0.003;
$bs = -0.03551851852;
$cs = -0.1553055556;
$ds = -0.2902116402;
$es = -0.02540079365;
$sp = ($as * pow($d1,4)) + ($bs * pow($d1,3)) + ($cs * pow($d1,2)) + ($ds * $d1) + $es;
$az = 1.976333333;
$bz = 30.84751852;
$cz = 172.4909722;
$dz = 419.5162831;
$ez = 519.8747579;
$zr = ($az * pow($d1,4)) + ($bz * pow($d1,3)) + ($cz * pow($d1,2)) + ($dz * $d1) + $ez;
$ag = -0.06333333333;
$bg = -0.7203703704;
$cg = -3.010277778;
$dg = -5.381375661;
$eg = 3.738769841;
$gn = ($ag * pow($d1,4)) + ($bg * pow($d1,3)) + ($cg * pow($d1,2)) + ($dg * $d1) + $eg;
$aw = 1.688666667;
$bw = 23.76837037;
$cw = 124.9339444;
$dw = 295.8872328;
$ew = 281.2755159;
$sw = ($aw * pow($d1,4)) + ($bw * pow($d1,3)) + ($cw * pow($d1,2)) + ($dw * $d1) + $ew;
$af = -0.00266666667;
$bf = 0.388;
$cf = 4.790666667;
$df = 19.55485714;
$ef = 28.76628571;
$fb = ($af * pow($d1,4)) + ($bf * pow($d1,3)) + ($cf * pow($d1,2)) + ($df * $d1) + $ef;
$an = -0.08333333333;
$bn = -0.9462962963;
$cn = -3.943055556;
$dn = -7.582671958;
$en = -5.23234127;
$dg = ($an * pow($d1,4)) + ($bn * pow($d1,3)) + ($cn * pow($d1,2)) + ($dn * $d1) + $en;
$wl = 299.7925 / $f;
print "Wavelength in meters = $wl<br>";
$wf = 983.5592 / $f;
print "Wavelength in Feet = $wf<br><br>";
print "Quad Dimensions in Wavelengths, Feet, and Meters:<br><br>";
printf( "Driver Side = %.4f WL or %.4f Feet or %.4f Meters<br>", $de / 4, $de / 4 * $wf, $de / 4 * $wl );
printf( "Driver Circumference = %.4f WL or %.4f Feet or %.4f Meters<br><br>", $de, $de * $wf, $de * $wl );
printf( "Reflector Side = %.4f WL or %.4f Feet or %.4f Meters<br>", $re / 4, $re / 4 * $wf, $re / 4 * $wl );
printf( "Reflector Circumference = %.4f WL or %.4f Feet or %.4f Meters<br>", $re, $re * $wf, $re * $wl );
printf( "Reflector-Driver Space = %.4f WL or %.4f Feet or %.4f Meters<br><br>", $sp, $sp * $wf, $sp * $wl );
printf( "Approximate Resonant Feedpoint Impedance = %.4f Ohms<br><br>", $zr );
printf( "Approximate Free-Space Gain = %.4f dBi<br>", $gn );
printf( "Approximate 2:1 VSWR Bandwidth = %.4f %% of Design Frequency<br>", $sw );
printf( "Approximate >20 dB F-B Ratio Bandwidth = %.4f %% of Design Frequency<br>", $fb );
printf( "Approximate Rate of Gain Change = %.4f dB per 1%% of Design Frequency<br><br>", $dg );
}
?>
</body>
</html>