CM Max Front-to-Back 3-Element Yagi Design, Enter Design Frequency and Element CM Diameter and set/select current units of measure. Model will calculate CM element lengths and spacing for maximum 180-degree front-to-back ratio. CM Element diameter range: 3E-4 to 1E-2 WL CM CE By L. B. Cebik, W4RNL (http://www.cebik.com) SY Fr=28.75 ' Enter Desired Frequency in MHz. SY WD=33 ' Enter Wire Diameter in mm/inch/WL. SY Hgh=0 ' Average Quad height above ground mtr (ft) SY Inp=mm ' Enable this line for diameter in mm 'SY Inp=in ' Enable this line for diameter in inch 'SY Inp=299.7925/Fr ' Enable this line for diameter in wavelengths SY D=(WD*Inp*FR)/299.7925 ' Get wire diameter in wavelengths SY D1=LOG(D)/log(10), D4=D1^4, D3=D1^3,D2=D1^2 SY Rel=-0.006330181818*D4-0.07473777778*D3-0.3305042424*D2-0.6517507937*D1-0.235223671 SY Drl=0.007257212121*D4+0.08419555556*D3+0.3603660606*D2+0.6680392063*D1+0.6865069654 SY Dil=0.00693430303*D4+0.07956444444*D3+0.3341948485*D2+0.5971698413*D1+0.595447158 SY Red=0.1003704242*D4+1.17784*D3+5.144348788*D2+9.942252381*D1+7.343132812 sy Did=0.06885818182*D4+0.8022222222*D3+3.476657576*D2+6.668892063*D1+5.092856861 - Red SY Scal=1 ' Use this line if output dimensions in meters. 'SY Scal=ft ' Use this line if output dimensions in feet. SY WL=299.7925/(Scal*Fr) ' Wavelength in Meters/Feet SY Refl=Rel*WL ' Reflector half length. SY Dril=Drl*WL ' Driver half length. SY Dirl=Dil*WL ' Director half side. SY Refd=Red*WL ' Reflector distance SY Dird=Did*WL ' Director distance SY Wr=D/2 * WL ' Wire radius. GW 1 11 0 -Dril Hgh 0 Dril Hgh Wr 'Driver GW 2 11 -Refd -Refl Hgh -Refd Refl Hgh Wr 'Reflector GW 2 11 Dird -Dirl Hgh Dird Dirl Hgh Wr 'Director GS 0 0 Scal GE EK LD 5 0 0 0 58000000 ' Copper wire EX 0 1 6 0 1 0 'GN 2 0 0 0 13 0.005 ' Use this line if ground used FR 0 1 0 0 Fr 0 EN