function showcredit()

{

var credit="Script programmed by Jens T.Saetre 13012001"



credit=  "Script programmed by Jens T.Saetre 13012001"

credit+="\n15012001 Added antenna gain calculations"

credit+="\n08122002 Changed layout"

window.alert(credit);



//var theResponse = window.prompt("Welcome?","Enter your name here.");

}





function log10(X)

{

return( Math.log(X)/Math.log(10)  );

// works OK !

}





function CalculateLoss()

{

var SurfaceIrregularities,Frequency,WaveLength,LossOfGain



SurfaceIrregularities=1*document.GainLoss.SurfaceIrregularities.value;

Frequency=document.GainLoss.Frequency.value;



WaveLength=300000000/(Frequency*1000000);   // in meter  1m=1000mm

//window.alert(WaveLength*1000);



LossOfGain=Math.exp(  -Math.pow(((4*Math.PI*SurfaceIrregularities)/(WaveLength*1000)),2 )      );

document.GainLoss.LossPercent.value=formatvalue((1-LossOfGain)*100, 5);

document.GainLoss.AntennaEfficiency.value=formatvalue(LossOfGain*100, 5);

document.GainLoss.LossdB.value=formatvalue(10*log10(LossOfGain), 5) ;

AntennaGain();



}





function AntennaGain()

{

var rxFrequency,Gain,AntennaDiameter,rxWaveLength,IdealGain



rxFrequency=1*document.GainLoss.Frequency.value;

AntennaDiameter=1*document.GainLoss.AntennaDiameter.value ;

rxWaveLength=300000000/(rxFrequency*1000000);  //meter 



IdealGain=10*log10(     Math.pow(((Math.PI*AntennaDiameter)/rxWaveLength),2));







document.GainLoss.IdealGain.value=formatvalue(IdealGain, 5) ;

document.GainLoss.AntennaGain.value=formatvalue((1*document.GainLoss.IdealGain.value+1*document.GainLoss.LossdB.value), 5) ; 









//window.prompt(Gain,"Test verdi");





}







function formatvalue(input, rsize) // Desimal avrunding

  {

   var invalid = "**************************";

   var nines = "999999999999999999999999";

   var strin = "" + input;

   var fltin = parseFloat(strin);

   if (strin.length <= rsize) return strin;

   if (strin.indexOf("e") != -1 ||

       fltin > parseFloat(nines.substring(0,rsize)+".4"))

      return invalid.substring(0, rsize);

   var rounded = "" + (fltin + (fltin - parseFloat(strin.substring(0, rsize))));

   return rounded.substring(0, rsize);

}