Transmission Line Basics VE3KL Session 1 Getting Started Project Overview Measure Zo, VF at Low Frequency First Look at TLDetails….it does the math Measure a 3.2 metre cable with various loads Keep a note book..data used later Applies to all sessions

Transmission Line Basics VE3KL Overview Study a 3.2 metre section of Rg-8X Use TLDetails..Does the Math for us Measure a 3.2 metre cable with various loads Design, build and test a simple antenna tuner Design, build and test a 4:1 transmission line Balun Design, build and test a two stub isolation filter

Transmission Line Circuit V- V+ Zo, Velocity, Length L = Inductance per metre [H] C = Capacitance per metre [F]

Example Zo, Velocity, VF, Length L = Inductance per metre [H] C = Capacitance per metre [F] RG213 L = 255 nH/metre C = 101 pF/m Zo = 50.2 Ohms Velocity = 1.97E8 metres/s VF = Velocity/(speed of light) = 0.65

Approximate Measurement of Zo,VF RG 8X, Length = 3 Approximate Measurement of Zo,VF RG 8X, Length = 3.2 metres long Length must be << one wavelength Zin ZL Zo, Velocity, Loss, Length Set ZL to an open circuit: Measure C at input Set ZL to a short circuit: Measure L at input Use an LC meter (Low frequency) Calculate Zo and VF from the formulas Record results in a notebook or computer

First Look at TLDetails Zin ZL Zo, Velocity, Loss, Length

Transmission Line Measurements RG 8X, 3.2 metres Aim 4170 VNA Zin ZL Zo, Velocity, Loss, Length ZL = 0 Find frequency where Zin = j50 (50 Ohm Inductance) ZL = ∞ Find frequency where Zin = -j50 (50 Ohm Capacitance) Check with TL Details http://en.wikipedia.org/wiki/Telegrapher%27s_equations