CM Equational model to calculate the dimensions of a resonant square 3-element CM quad beam, optimized for wide band width. CM All equations calibrated to NEC antenna modeling software for wire diameters CM from 3.16E-5 to 1E-2 wavelengths within about 0.5% from 3.5 - 250 MHz. CM CE By L. B. Cebik, W4RNL (http://www.cebik.com/quad/q3le.html) SY Fr=14.175 ' Enter Desired Frequency in MHz. SY WD=1.62814 ' Enter Wire Diameter in mm/inch/WL. (0.0641 inch) SY Hgh=0 ' Average Quad height above ground in Meters (Feet) 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 L=.4342945*LOG(D*10^5) SY LL=L^2, LM=LL*.0128, LN=LM+1.0413, D1=.4342945*LOG(D) SY AD=.00064, BD=.01044148148, CD=.06484444444, DD=.1886626455, ED=1.232080635 SY DE=(AD*(D1^4))+(BD*(D1^3))+(CD*(D1^2))+(DD*D1)+ED SY AR=.0009333333333, BR=.01915555556, CR=.13983333333, DR=.4587492063, ER=1.64042381 SY RE=(AR*(D1^4))+(BR*(D1^3))+(CR*(D1^2))+(DR*D1)+ER SY AI=-.0012, BI=-.0209037037, CI=-.13021111111, DI=-.3498137566, EI=.5941126984 SY IR=(AI*(D1^4))+(BI*(D1^3))+(CI*(D1^2))+(DI*D1)+EI SY AS=-.0033, BS=-.03927777778, CS=-.1724583333, DS=-.3239603175, ES=-.04951547619 SY SP=(AS*(D1^4))+(BS*(D1^3))+(CS*(D1^2))+(DS*D1)+ES SY AP=-.004866666667, BP=-.06262962963, CP=-.29347222222, DP=-.6174457672, EP=-.2289269841 SY IP=(AP*(D1^4))+(BP*(D1^3))+(CP*(D1^2))+(DP*D1)+EP 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 Ds=DE/8 * WL ' Driver half side. SY Rs=RE/8 * WL ' Reflector half side. SY Rd=SP * WL ' Reflector-Driver Space. SY Is=IR/8 * WL ' Director half side. SY Id=IP * WL ' Director-Driver Space. SY Wr=D/2 * WL ' Wire radius. GW 1 11 0 -Ds HGH-Ds 0 Ds HGH-Ds Wr GW 2 11 0 Ds HGH-Ds 0 Ds HGH+Ds Wr GW 3 11 0 Ds HGH+Ds 0 -Ds HGH+Ds Wr GW 4 11 0 -Ds HGH+Ds 0 -Ds HGH-Ds Wr GW 11 11 -Rd -Rs HGH-Rs -Rd Rs HGH-Rs Wr GW 12 11 -Rd Rs HGH-Rs -Rd Rs HGH+Rs Wr GW 13 11 -Rd Rs HGH+Rs -Rd -Rs HGH+Rs Wr GW 14 11 -Rd -Rs HGH+Rs -Rd -Rs HGH-Rs Wr GW 21 11 Id -Is HGH-Is Id Is HGH-Is Wr GW 22 11 Id Is HGH-Is Id Is HGH+Is Wr GW 23 11 Id Is HGH+Is Id -Is HGH+Is Wr GW 24 11 Id -Is HGH+Is Id -Is HGH-Is Wr GS 0 0 Scal GE 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 for Calc's above ground. FR 0 1 0 0 Fr 0 'CM Enable below SY lines to see some performance predictions. Use 'CM 'View->Symbol conversion (SHFT+Y)' on 'Geometry (F3)' window to 'CM see intermediate and resulting values ' 'SY AZ=-2.227066667, BZ=-26.75247407, CZ=-115.9142556, DZ=-217.8183323, EZ=-79.59203175 'SY ZR=(AZ*(D1^4))+(BZ*(D1^3))+(CZ*(D1^2))+(DZ*D1)+EZ ' Feedpoint imp. 'SY AG=-.07, BG=-.7877777778, CG=-3.350833333, DG=-6.143888889, EG=5.104166667 'SY GN=(AG*(D1^4))+(BG*(D1^3))+(CG*(D1^2))+(DG*D1)+EG ' Free space gain 'SY AW=-.05847333333, BW=-.5028392593, CW=-.4586494444, DW=6.080227037, EW=17.61091389 'SY SW=(AW*(D1^4))+(BW*(D1^3))+(CW*(D1^2))+(DW*D1)+EW ' 2:1 SWR bandwidth 'SY AF=.11695666667, BF=1.717985556, CF=9.6510925, DF=25.23848992, EF=27.78167988 'SY FB=(AF*(D1^4))+(BF*(D1^3))+(CF*(D1^2))+(DF*D1)+EF ' %BW for > 20dB F/B 'SY AN=-.04666666667, BN=-.5414814815, CN=-2.302777778, DN=-4.364074074, EN=-3.092777778 'SY DG=(AN*(D1^4))+(BN*(D1^3))+(CN*(D1^2))+(DN*D1)+EN ' Gain change / %Fr change EN