HALF TURN QUADRIFILAR HELIX AERIAL USING 10mm COPPER TUBE BASIC DESIGN CRITERIA Frequency 145 MHz Aspect ratio of Height to Diameter 1.45 Mean Perimeter to Wavelength ratio 1.07 Deviation of Perim. to Wl. ratios +/- 3.27 % Small loop Perimeter to Wavelength ratio 1.035011 Small loop Diameter to Wavelength ratio .1649298 Small loop Height to Wavelength ratio .2391482 Large loop Perimeter to Wavelength ratio 1.104989 Large loop Diameter to Wavelength ratio .1760808 Large loop Height to Wavelength ratio .2553172 DIMENSIONS INCHES MILLIMET Wavelength 81.39913 2067.53 SMALL LOOP Dimensions to tube centres Diameter 13.42514 340.998 Height 19.46645 494.447 Length of helix 28.69936 728.963 Perimeter 84.249 2139.92 Dimensions of tubes less 4 mm per joint for 90 deg. end feed elbows Diameter tube length less 8 mm 13.11018 332.998 Half diameter tube length less 8 mm 6.397609 162.499 Helix tube length less 8 mm 28.3844 720.963 Formed radius for helix tube 12.70018 322.584 Formed end lift for helix tube (each end) 2.993806 76.0426 LARGE LOOP Dimensions to tube centres Diameter 14.33282 364.053 Height 20.7826 527.877 Length of helix 30.63975 778.249 Perimeter 89.94514 2284.60 Dimensions of tubes less 4 mm per joint for 90 deg. end feed elbows Diameter tube length less 8 mm 14.01786 356.053 Half diameter tube length less 8 mm 6.851452 174.026 Helix tube length less 8 mm 30.32479 770.249 Formed radius for helix tube 13.55885 344.394 Formed end lift for helix tube (each end) 3.19622 81.1839