FREQUENCY MODULATION APPROACH BASED ON SPLIT-RING RESONATOR LOADED BY VARACTOR DIODE

Abstract

In the paper, an approach to frequency modulation is presented using a split-ring resonator (SRR) loaded by a varactor diode. The modulation occurs due to the continuous time variation of capacitance of the varactor diode via changing of its bias voltage by the signal which is necessary to modulate. The modulation signal is used for bias voltage. As a source of a carrier signal, one more extra magnetic loop antenna is utilized which is coupled with the SRR via near-field interaction. Investigation of two types of signals (harmonic and chaotic) was performed for modulation in the paper. It is shown that it is possibile to provide the frequency modulation with deviation Δfd = ±80 MHz which covers the frequency range 0.95…1.11 GHz for a 1 GHz carrier signal when a SMV1231 varactor diode is used. The major advantages of the suggested approach are the very simple design and ability to easily define the required values of frequency deviation through tuning of the bias voltage magnitude range of the varactor diode. Therefore, the presented investigation and results can be useful in the manufacturing of low-cost radio components.

Keywords

• frequency modulation
• varactor diode
• split-ring resonator
• frequency range
• frequency deviation