Counter-Wound Normal-Mode Helical Antenna as an Electrically Small Electro-Quasi-Static Exciter

An electrically small electro-quasi-static exciter is demonstrated using a counter-wound normal-mode helical antenna. The arms are counter-rotated to cancel the generation of magnetic fields in the quasi-static regime. The field equations are derived and verified to show the degradation of magnetic fields with minimal effects to the electric field. The long wire lengths give sinusoidal current distribution and fields that are not strongly dependent on the feed structure. As a result, the measured electro-quasi-static field agrees well with the dipole behavior over long ranges. In addition, the circuit model for the antenna is presented and verified with measurements.