Boom correction for
through the boom insulated elements on 2 meters & 70cm.
Proven accurate for boom diameters smaller than .055 wavelengths.
Formula: C = 12.5975*B  114.5*B^2
Correction for 2 meters G3SEK  

Boom diameter  Correction  Add  
Inches  mm  Percent  Inches  mm 
0.750  19.050  10.56%  +0.792  +2.02 
0.875  22.225  12.14%  +0.1062  +2.70 
1.000  25.400  13.66%  +0.1366  +3.47 
1.125  28.575  15.13%  +0.1702  +4.32 
1.250  31.750  16.54%  +0.2068  +5.25 
1.375  34.925  17.90%  +0.2462  +6.25 
1.500  38.100  19.21%  +0.2882  +7.32 
1.750  44.450  21.67%  +0.3792  +9.63 
Correction
for IØJXX's 2 meters antennas 


Boom diameter 
Correction 
mm  mm 
20  +1.50 
22  +1.75 
25  +2.50 
30  +4.00 
35  +5.40 
40  +7.00 
Correction
for DJ9BV's 2 meters antennas 


Boom diameter 
Correction 
mm  mm 
20  +2.00 
25  +3.00 
30  +5.00 
35  +6.00 
Correction for 70 cm G3SEK  

Boom diameter  Correction  Add  
Inches  mm  Percent  Inches  mm 
0.787  20.000  25.00%  0.1968  +5.00 
1.000  25.400  20.00%  0.2362  +6.00 
1.125  28.575  24.50%  0.2756  +7.00 
1.250  31.750  25.20%  0.3149  +8.00 
1.375  34.925  25.77%  0.3543  +9.00 
Correction used by K1FO on 70 cm  

Boom diameter  Correction  Add  
Inches  mm  Percent  Inches  mm 
0.875  22.225  28.98%  0.2536  +6.44 
1.000  25.400  31.97%  0.3198  +8.12 
1.125  28.575  33.49%  0.3769  +9.57 
1.250  31.750  36.00%  0.4501  +11.43 
1.375  34.925  38.00%  0.5226  +13.27 
Correction used by VE7BQH on 70 cm  

Boom diameter  Correction  Add  
Inches  mm  Percent  Inches  mm 
0.630  16.000  22.94%  0.1445  +3.67 
0.750  19.050  25.93%  0.1945  +4.94 
0.875  22.225  22.50%  0.1969  +5.00 
1.000  25.400  27.56%  0.2756  +7.00 
1.125  28.575  31.50%  0.3544  +9.00 
1.250  31.750  33.67%  0.4210  +10.69 
1.375  34.925  33.33%  0.4584  +11.64 
Correction
for 70 cm IØJXX antennas 


Boom diameter 
Correction 
mm  mm 
20  +5.7 
22  +6.2 
25  +7.7 
30  +10.0 
35  +12.8 
40  +15.1 
Correction
for DJ9BV's 


Boom diameter 
Correction 
mm  mm 
20  +5.00 
25  +7.00 
30  +10.00 
35  +12.00 
Note: there is no difference in correction factor for round or square booms.
The following are some average
element diameter corrections for 2m to scale an antenna for a
different diameter element.
It is not so simple as just adding a simple linear correction as
the overall taper changes depending on the diameter of element.
As a consequence the correction varies from reflector to last
director. Eg: 6.25mm to 5mm diameter correction on a 10 el. DJ9BV
antenna is 2 mm at the reflector and 6.91mm at director 8.
The above was calculated using the YOC 5.0 scaling feature.
Element diameter correction (2 meters)  

Diameter (mm)  6.35  5.00  4.76  4.00  2.00 
Add (mm)  0.00  4.50  5.00  8.00  12.00 
Correction
factor for Cushcraft and Cudee style mounted elements (2 meters) 


Company  Inches  mm 
Cushcraft  0.25  6.35 
Cudee  0.25  6.35 
Dopt = (wavelength/2) * sin(beamwidth/2)
Good results can be obtained down
to 90 percent of the above formula if a smaller stacking frame is
desired.
Closer stacking than 90 percent of DL6WU's formula will result in
a degradation of G/T.