ETS-Lindgren 3103 Conical Log Spiral Antenna 100 MHz - 1 GHz

The Model 3103 Conical Log Spiral is made with spiral windings of coaxial cable attached to the outside of a fiberglass cone.

Outside windings improve heat dissipation. This cone is attached to a delrin rod equipped with an aluminum base. The antenna mount base accepts standard 1/4 in x 20 threads from a tripod.

Once used exclusively for MIL-STD and SAE testing, conical log spiral antennas are effective for other types of measurements too. For example they can be used for close-in ""quick-looks"" to find the spectral characteristics of RF emissions. For immunity testing, conical log spirals generate reasonable field strengths with modest power input. By placing conical log spiral antennas in a vertical position with respect to the ground plane, they can also be used as omni-directional, horizontally polarized antennas for electromagnetic site surveys.

The Model 3103 conical log spiral antenna is similar to Models 3101 and 3102 except that it has the lowest frequency range and it is largest in size. The design is patterned on NASA drawings.