天线增益计算器
计算天线的方向性增益。
m
MHz
Propagation Delay
50.54 ns
Electrical Length1.8 °
Wavelength in Line1.979 m
Propagation Delay vs Physical Length
公式
## Transmission Line Propagation ### Formulas **v = c x VF** (propagation speed) **Delay = Length / v** **Electrical Length = 360 x Length / wavelength_in_line** Transmission line effects matter when the line is a significant fraction of the wavelength (typically > 1/10).
计算示例
10 m coax (VF = 0.66) at 100 MHz.
- 01Speed = 299.792 x 0.66 = 197.86 Mm/s
- 02Delay = 10 / 197860000 = 50.5 ns
- 03Wavelength in line = 197.86 / 100 = 1.979 m
- 04Electrical length = 360 x 10 / 1.979 = 1819 degrees
常见问题
When do transmission line effects matter?
When the line length exceeds about 1/10 of the wavelength. At 100 MHz with VF=0.66, this is about 20 cm.
What happens at quarter-wavelength?
A quarter-wave line transforms impedance: Z_in = Z0^2 / Z_load. This is used for impedance matching.
What is velocity factor?
The ratio of signal speed to the speed of light. Determined by the dielectric material surrounding the conductors.
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