This calculator gives the turns ratio of an RF transformer. Enter the input and output impedance.
Formula
Np/Ns = √(Zp/Zs)
where
- Np = Number of turns in the primary coil
- Ns = Number of turns in the secondary coil
- Zp = Input or Primary impedance
- Zs = Output or Secondary impedance
Background
An RF transformer is a passive device that “transforms” or converts an impedance, voltage or current to another desired value.
In addition, a transformer can also be used to isolate DC, reject common
mode signals, and convert balanced impedance to unbalanced or vice versa.
The picture below shows a transformer by Mini-circuits.
RF transformers are specified to operate over a frequency range. The turns ratio is a key parameter and refers to the ratio of the secondary to primary impedance Zs/Zp.
Just like any other RF component, transformers have insertion loss, return loss that vary with frequency and a maximum input power level.