The SM3 (Aluminium) is a unity gain broad band base folded dipole antenna. It covers the entire range from 136 MHz to 175 MHz. It is supplied with a standard boom length to facilitate 1⁄4 wave antenna to mast spacing.
The dimension is taken from the centreline of the dipole element to the mast face.
The antenna array is DC grounded for lightning protection and is vertically polarised and can be stacked in different configurations to give desired gain and field patterns.