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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
VelocitySize
O.D.
in Inches
at 50MHzat 900 MHz
LMR-100 50 5.122.8 .66 .110
LMR-200 50 2.39.9 .83 .195
LMR-240 50 1.77.6 .84 .240
LMR-400 50 1.14.5 .85 .405
LMR-600 50 .552.9 .87 .590
LMR-900 50 .371.7 .87 .870
LMR-1200 50 .271.3 .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
VelocityMax voltage
in RMS KV
at 50MHzat 1GHz
RG6U751.511 dB.78 (foam)0.6kv
RG8U521.29.66 (poly)5kv
RG8U501.1 .78 (foam)0.6
RG8X50 13.5.842.5
RG9U511.6 .66 "5
RG11U751.39.66 (poly)5
RG11U751.0 .78 (foam)0.6
22B/U95 2.166 (poly)?
RG55B/U53.5 16.5 1.9kv
RG58U533.120.66 (poly)1.9kv
RG58U503.2 .78 (foam)0.2kv
RG59U732.411.5.66 (poly)2.3
RG59U752.1 .78 (foam)0.3kv
RG62U931.98.5.84 (air & poly)0.7kv
RG71U931.98.5.84 (air & poly)0.7
RG108A/U78 26.2 1.0
RG122U504.529.2.66 (poly)1.9
RG140U75 13 2.3
RG141U502.113.69 (Teflon)1.9
RG142U502.713.69 (Teflon)1.9
RG174U506.631.66 (poly)1.5
RG178U5010.545.69 (Teflon)1.0
RG179U758.525.69 (Teflon)1.2
RG180U954.616.5.69 (Teflon)1.5
RG187U758.525.69 (Teflon)1.2
RG188U509.630.69 (Teflon)1.2
RG196U5010.545.69 (Teflon)1.2
RG210U93 3.1 0.75
RG213U501.69.66 (poly)5
RG214U501.69.66 (poly)5
RG217U50 5.8.66 (poly)7
RG218U50 3.8.66 (poly)11Kv
RG219U50 3.8 11
RG223U503.116.5.66 "1.9
RG225U50 7.5 5
RG303U502.113.69 (Teflon)1.9
RG302U75 13 2.3
RG316U509.430.69 (Teflon)1.2
RG393U50 7.5 5
RG400U50 13.69 (Teflon)1.9
RG401U50 7.5(semi-rigid)3
RG402U50 13(semi-rigid)2.5
RG405U5022 (semi-rigid)2
821875 20 0.6
828175 9.2 2.9
991350 4.5 0.6
991450 6 0.6


Common
Name
Impedance
in Ohms
Loss in dB
per 100 feet
VelocityMax voltage
in RMS KV
at 50MHzat 1GHz
Thicknet
(old ethernet)
501.2 .78 (foam)0.6
"Twin Lead"3000.8 and worse
when wet!
 .80 (poly)?