,: ,,: ,:"VHF YAGI BEAM DESIGN" ,: (O,"=")* , :"THIS PROGRAM IS TO DESIGN BEAMS IN THE ";: :" 144 - 220 - 440 Mhz BANDS": h( ,:"WHICH HAVE MORE THAN ";: :" 3 ELEMENTS": -  , : :"IT WAS ADAPTED TO COLOR FROM A PROGRAM ON THE PDS DISK AR 1.0"2 ,#: :"[ENTER]"< ,F ,&:ZZ$: ZZ$ "" FP ,,:Vd:This program calculates the dimensions of a VHF Yagi antenna.^n:}x:Design assumptions are:: 1. Driven element length in inches is 5600/frequency in MHZ.: 2. The reflector is 5% longer than the driven element.T: 3. Reflector and first director spacing is 0.2 wavelengths from driven.: 4. The first director is 5% shorter than the driven element.: Subsequent director lengths are calculated by adding 1% to*: the shortening factor of the previous director. For example,n: the 2nd director is 6% shorter than the driven element,: the 3rd is 7% shorter, the 4th, 8% shorter, etc.: 5. Director spacing is 110% of previous spacing. Spacing starts: at 0.2 wavelengths.:d: The program is well documented via remarks, so any of the above: assumptions may be easily changed.:: Program COLOR mods by R. Thwing K4EDE P.O. Box 40 Columbus, NC 28722 :>:-------------------- PROGRAM BEGINS --------------------------------------K: ,"" VHF YAGI BEAM DESIGN"::::", I. , : "THE OUTPUT OF THIS PROGRAM IS TO THE MONITOR SCREEN"/ , : :"PRESS [SHIFT]+[PRINT] FOR HARD COPY WHEN WANTED"0O1  , : :"DO YOU WANT TO USE PRINTER? Y/N "p2  ,*:ZZ$: ZZ$"" 23 ZZ$ "Y" ZZ$ "y" ' : 44 ,: :"HIT [ENTER] TO CONTINUE";ZZ: 5:6 ,:"WHAT FREQUENCY (MHZ) ";FREQO7 FREQ  FREQ  :"FREQ OUT OF VHF BAND..REENTER FREQ": : 6|@"HOW MANY ELEMENTS (3 MINIMUM) ";ELNO:A ELNO  :"TOO FEW ELEMENTS...TRY AGAIN": : @JWL  .FREQ :wavelength in free space (inches)%TDR FREQ :driven element length (inches)M^RF DR ff :reflector lengthwhSPR WL L~ :reflector spacingrPL() DR 33s:first director length|SPP() WL L~ :first director spacing I  (ELNO )GSPP(I) SPP(I)  :each director spacing 10% greater than previousPL(I) DR (d ( I)) #z :director lengthLN1 LN1 SPP(I) :keep track of overall length  X(X) (Xd) #z :function to round off printing to 2 dec.>LNT SPR SPP() LN1 :total beam lengths ,:"DESIGN DATA FOR VHF YAGI BEAM ANTENNA: "y"---- DESIGN FREQUENCY IS";FREQ;" MHZ""---- TOTAL NUMBER OF ELEMENTS IS";ELNO #);"LENGTH IN INCHES""REFLECTOR";();X(RF)A"REFLECTOR TO DRIVEN";));X(SPR)[&"DRIVEN";();X(DR)0"DRIVEN TO 1st DIRECTOR";));X(SPP()):"1st DIRECTOR LENGTH";();X(PL())DN I  (ELNO )X"DIRECTOR No.";I;" LENGTH IS";X(PL(I));" INCHES"Ab"SPACED";X(SPP(I));" INCHES FROM DIRECTOR No.";IGlMv"------ OVERALL BEAM LENGTH IS";X(LNT);" INCHES ------" ,#: :"[SPACE BAR]"AA$: AA$""  :  ,: :"WHAT NOW?"+ ,:"DO ANOTHER DESIGN?...........................A"i ,:"RETURN TO BASIC..............................B" ,:"RETURN TO MAIN MENU..........................M" : ,:"RETURN TO MS-DOS.............................D" : ,ZZ$: ZZ$"" , ZZ$ "A" : 6A ZZ$ "B" :^ ZZ$ "M" "MAINMENU"s ZZ$ "D"  :   ,:: :  ,:"ARE YOU SURE (Y)es/(N)o ?": ,: :"<<<<< A YES WILL CLEAR BASIC!! >>>>>"*AA$: AA$ "" *4 AA$ "Y" ,:/> ,: p'A( y): A , : :"PRINTER NOT READY ": '' : , :" ":