Sophisticated Helix Antenna Design with matching Coax to 50 Ω

helix.js

function mehrWind() { x = document.generator.n.value * 1; x = x + 1 ; document.generator.n.value = x.toFixed(0) ; rechnen();}
		function wenigerWind() { x = document.generator.n.value * 1; x = x - 1 ; if (x<1) x=1; document.generator.n.value = x.toFixed(0) ; rechnen();}
		function mehrCond() { x = document.generator.d4.value * 1; x = x + 0.1 ; document.generator.d4.value = x.toFixed(2) ; rechnen();}
		function wenigerCond() { x = document.generator.d4.value * 1; x = x - 0.1 ; if (x<0.1) x=0.1; document.generator.d4.value = x.toFixed(2) ; rechnen();}
		
		function rechnen()
		{
		    var freq;
		    
		    freq = document.generator.freq.value  * 1;
		    n = document.generator.n.value * 1;
		    d4 = document.generator.d4.value * 1;
		
		    var lambda = 300000000 / ( freq * 1000 ) ;
		    var pi = 3.141592653 ;
		    
		    var d3 = lambda * 1.1;
		    
		    var l1 = lambda / 4 ;
		    
		    var steigung = l1 ;
		    var umfang = lambda ;
		    var d2 = umfang / pi ;
		    
		    var impedanz_helix = 140 * pi * d2 / lambda ;
		    var impedanz_quelle = 50 ;
		    
		    var impedanz_matcher = Math.sqrt( impedanz_helix * impedanz_quelle ); // lambda viertel lang !!!
		    var outer_diameter = d4 * Math.pow(10,(impedanz_matcher / 138 )) ;
		   
			var l2 = n * steigung;
			
			var gain = 11.8 + 10* Math.log(pi * pi * d2 *d2 * n * steigung / ( lambda * lambda * lambda )) / Math.log(10) ;

		
		    document.generator.l1.value=l1.toFixed(2);
		    document.generator.d1.value=outer_diameter.toFixed(2);
		    document.generator.d3.value=d3.toFixed(2);
		    document.generator.lambda.value=lambda.toFixed(2);
		    document.generator.d2.value=d2.toFixed(2);
		    document.generator.l2.value=l2.toFixed(2);
		    document.generator.gain.value=gain.toFixed(2);
		    document.generator.R.value=impedanz_helix.toFixed(2);
		
		}