Handyform coaxial cable, 60Ω, PTFE, 4.1mm

60Ω coaxial cable is often used also as λ/4 matching between 50 and 75Ω.

To demonstrate the operation of the λ/4 transormer we have verified the correct impedance transformation between 50 and 75Ω at the frequency of 127 MHz.

Z = √50 x 75 = 61Ω

λ/4C = λ/4 x V_F
λ/4C = Matching line 1/4 wavelength on cable
λ/4 = 1/4 wavelength at 128 MHz
V_F = Velocity factor 70% (for PTFE is 0.70)
λ/4 = 300/127 x 1/4 = 590.5mm
λ/4C = 590.5 x 0.70 = 413mm (this is the real length of the cable)

The graph below shows the return loss or impedance matching at the frequency of 127 MHz, as you can see the result is very good.