Radio frequency (RF) is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals. RF usually refers to electrical rather than mechanical oscillations, although mechanical RF systems do exist.
Electric currents that oscillate at radio frequencies have special properties not shared by direct current or alternating current of lower frequencies. The energy in an RF current can radiate off a conductor into space as electromagnetic waves (radio waves); this is the basis of radio technology. RF current does not penetrate deeply into electrical conductors but flows along their surfaces; this is known as the skin effect. For this reason, when the human body comes in contact with high power RF currents it can cause superficial but serious burns called RF burns.
In order to receive radio signals an antenna must be used. However, since the antenna will pick up thousands of radio signals at a time, a radio tuner is necessary to tune in to a particular frequency (or frequency range). This is typically done via a resonator in its simplest form, a circuit with a capacitor and an inductor forming a tuned circuit. Radio frequency (RF) energy has been used in medical treatments for over 75 years, generally for minimally invasive surgeries, using radiofrequency ablation and coagulation, including the treatment of sleep apnea. Magnetic resonance imaging (MRI) uses radio frequency waves to generate images of the human body.
People are requesting walkie-talkie and RF remote control schematics, so here are some. Building these circuits needs special equipment and expertise in RF circuits. If you have no experience in RF, I suggest that you choose the easy way and buy a ready-made RF module. Otherwise you can realize you have an exact copy of a circuit in your hand, still it doesn't work the way it should. 100s of RF circuits for every hobbyist, technician, student, and design professional. An nice reference tool which includes lots of rf circuits. look at these circuit ideas, some of them may need some modification if they are to work as advertised. Ideas along with pretty good descriptions for each circuit.