Reactance:

Things are easy when there is no reactance in an alternating current circuit using transformers. But often, especially in the radio-frequency circuits, pure resistance does not occur naturally. It has to be attained making use of inductors or capacitors or both to cancel the reactance out. Reactance makes the perfect match impossible, does not matter what the turns ratio or Zo of transformer. A small amount of reactance can be tolerated at the lower radio frequencies (below 30 MHz). A near perfect match becomes more significant at higher frequencies.

The behavior of reactance, as it is coupled through the transformer windings, is very much complicated for a thorough analysis. However if you are interested in delving into it, there are good engineering texts which deal with the mathematical glory. The inductive and capacitive reactances are having opposite effect, and that their magnitudes can vary. If the load presents complex impedance R+jX, with X which is not equal to zero, it is always possible to cancel out the reactance X by adding an equal and opposite reactance (-X) in circuit. This can be done by connecting an inductor or capacitor in series with load.

For the radio communications over a wide band range, adjustable impedance matching and reactance canceling networks can be placed between the transmitter and an antenna system. This type of device is called as transmatch and is popular among the radio hams, which use frequencies ranging from 1.8 MHz to microwave spectrum.