you need
  • wires of different sections, paper, glue, plastic cylinder, knife, scissors
basis coil inductance - conductor.Around the conductor with current flowing through the magnetic field is always present.The strength of this field depends on the strength of the current in a conductor.Another way to strengthen the magnetic field - to roll the conductor into a spiral.This is nothing more than a coil inductance .The smaller the diameter of the coil, the more it turns, the stronger the magnetic field generated by the coil.Radio amateurs are usually wound coils alone.
inductance is the ability of the coil to create a magnetic field.Measured inductance in Henry (H).
inductance coils not produced in the form of stand
ard components with standard characteristics, and are calculated and manufactured for each specific device individually.Therefore, in the manufacture of the coil you need to first take into account the characteristics of the input and output of your radio installation.
for VHF and shortwave resonant circuits manufactured coil with a few turns and thick wire.Some of these reels have a skeleton.
to transmit and receive radio signals in medium and long wavelengths used multiturn coil (single-layer and multi-layer).To produce a framework for these reels you'll need paper or plastic.
number of turns of the coil when setting up radios and other equipment necessary to select experimentally changing the inductance of the coil.It is possible to do so and domatyvaniem unwinding of coil turns, but this method is not entirely practical.Most often, the coil is placed inside the core of the Retractable special magnetic materials.This may be alsifer (an alloy of aluminum, iron and silicon).
magnetic core concentrates the magnetic field of the coil than increase its inductance.At the same time you can reduce the number of turns of the coil, which causes a decrease in its size and dimensions of the radio.