Printed Self-Matched Normal Mode Helix Antenna
Image of the Printed Self-Matched Normal Mode Helix Antenna.

Normal mode helix antennas (NMHA) are often used for handheld radio transceivers and mobile communications applications. The printed self-matched NMHA is naturally matched to 50 Ω, thus avoiding the typical design challenge of matching similar structures at resonance.

It exhibits properties similar to other NMHAs, namely: It is compact (with the total height being typically 0.14 λ), it is vertically polarized and omni-directional and has a bandwidth of approximately 3%.

The helical structure consists of two (inner and outer) metallic helical strips of equal width, with a central dielectric section between them.

Typical gain at the center frequency
Typical gain at the center frequency
Typical reflection coefficient versus frequency