A Helical antenna is made from a coiled, small-diameter spring which is flexible and coated in plastic. The name comes from the conducting wire inside which is coiled in the form of a helix. It responds to electromagentic fields with circular polarization. A pair of these antennas is commonly attached directly to RF Code readers for indoor applications. A ¼ wave Whip antenna is sometimes recommended for greater efficiency.
Specifications:
Operation
Frequency: 433.92 MHz
Gain: -4 dB
Pickup Angle: Omni-Directional
Polarization: Vertical or horizontal
Impedance: 50 Ohms
Termination: Female
Material: Coated helical
Length: 5.5 in
Diameter: 0.4 in
Joint Configuration: Straight or right angle
Connector Mount: SMA female