ham radio

Coax

Cable Losses

All Coax cable is given in losses per 100ft

Db Loss % Loss
.1 dB 2.2 %
.2 dB 4.5 %
.3 dB 6.6 %
.4 db 8.7 %
.5 dB 10.8 %
.6 dB 12.9 %
.7 dB 15 %
.8 dB 16.8 %
.9 dB 18.7 %
1 dB 20 %
2 dB 36 %
3 dB 50 %
4 dB 60 %
5 dB 68 %
6 dB 75 %
8 dB 84 %
9 dB 87.5 %
10 dB 90 %

So 100 Ft of RG8 with db Loss of .9dB with input power of 200W gives anteanna power of

(1-.187) * 200 => 167 W

The loss is simply

.187 *200 -> 33 Watts

Calculator

Excelent calc at Calc