Antenna Calculator

Velocity:
Leave this set to .95 for antenna wire lengths(when constructing antennas).

When building a phasing harness to feed 2 antennas from one transmitter-
Cut 2 equal, odd 1/4 wavelengths(i.e. 1/4, 3/4, 1 1/4, 1 3/4)-
75 ohm impedance of coax using the Velocity(charts below).
Add connectors. Tie them together with a T connector.

Wavelength(decimal equivalents):
1/8=.125, 1/4=.250, 3/8=.375, 1/2=.50, 5/8=.625, 3/4=.750, 7/8=.875

(Light Speed * Velocity * WaveLength) / Frequency(MHz) = Wire Length

( * * ) / =

speed of light = 299,792,458 metres per second(according to wikipedia).
1 meter = 39.37007874 inches
11,802,852,677.1 inches/12 inches per foot.
983,571,056.427 feet/Hz
thus 983.571 feet/1MHz

Common Coaxial Cables
Common
Name		 Impedance
in Ohms		 Loss in dB
per 100 feet		 Velocity Size
O.D.
in Inches
at 50MHz at 900 MHz
LMR-100 50 5.1 22.8 .66 .110
LMR-200 50 2.3 9.9 .83 .195
LMR-240 50 1.7 7.6 .84 .240
LMR-400 50 1.1 4.5 .85 .405
LMR-600 50 .55 2.9 .87 .590
LMR-900 50 .37 1.7 .87 .870
LMR-1200 50 .27 1.3 .88 1.200
LMR-1700 50 .15 .94 .89 1.670

Common Coaxial Cables
Common
Name		 Impedance
in Ohms		 Loss in dB
per 100 feet		 Velocity Max voltage
in RMS KV
at 50MHz at 1GHz
RG6U 75 1.5 11 dB .78 (foam) 0.6kv
RG8U 52 1.2 9 .66 (poly) 5kv
RG8U 50 1.1   .78 (foam) 0.6
RG8X 50   13.5 .84 2.5
RG9U 51 1.6   .66 " 5
RG11U 75 1.3 9 .66 (poly) 5
RG11U 75 1.0   .78 (foam) 0.6
22B/U 95   2.1 66 (poly) ?
RG55B/U 53.5   16.5   1.9kv
RG58U 53 3.1 20 .66 (poly) 1.9kv
RG58U 50 3.2   .78 (foam) 0.2kv
RG59U 73 2.4 11.5 .66 (poly) 2.3
RG59U 75 2.1   .78 (foam) 0.3kv
RG62U 93 1.9 8.5 .84 (air & poly) 0.7kv
RG71U 93 1.9 8.5 .84 (air & poly) 0.7
RG108A/U 78   26.2   1.0
RG122U 50 4.5 29.2 .66 (poly) 1.9
RG140U 75   13   2.3
RG141U 50 2.1 13 .69 (Teflon) 1.9
RG142U 50 2.7 13 .69 (Teflon) 1.9
RG174U 50 6.6 31 .66 (poly) 1.5
RG178U 50 10.5 45 .69 (Teflon) 1.0
RG179U 75 8.5 25 .69 (Teflon) 1.2
RG180U 95 4.6 16.5 .69 (Teflon) 1.5
RG187U 75 8.5 25 .69 (Teflon) 1.2
RG188U 50 9.6 30 .69 (Teflon) 1.2
RG196U 50 10.5 45 .69 (Teflon) 1.2
RG210U 93   3.1   0.75
RG213U 50 1.6 9 .66 (poly) 5
RG214U 50 1.6 9 .66 (poly) 5
RG217U 50   5.8 .66 (poly) 7
RG218U 50   3.8 .66 (poly) 11Kv
RG219U 50   3.8   11
RG223U 50 3.1 16.5 .66 " 1.9
RG225U 50   7.5   5
RG303U 50 2.1 13 .69 (Teflon) 1.9
RG302U 75   13   2.3
RG316U 50 9.4 30 .69 (Teflon) 1.2
RG393U 50   7.5   5
RG400U 50   13 .69 (Teflon) 1.9
RG401U 50   7.5 (semi-rigid) 3
RG402U 50   13 (semi-rigid) 2.5
RG405U 50 22   (semi-rigid) 2
8218 75   20   0.6
8281 75   9.2   2.9
9913 50   4.5   0.6
9914 50   6   0.6

Common
Name		 Impedance
in Ohms		 Loss in dB
per 100 feet		 Velocity Max voltage
in RMS KV
at 50MHz at 1GHz
Thicknet
(old ethernet)		 50 1.2   .78 (foam) 0.6
"Twin Lead" 300 0.8 and worse
when wet!		   .80 (poly) ?