The present invention provides a light weight, modular and rigid structure for supporting the transmitter loop of an airborne electromagnetic system. The airborne electromagnetic surveying system comprises a tow assembly connected to an aircraft, the tow assembly including a transmitter section comprising a transmitter coil for generating a primary electromagnetic field that induces a secondary electromagnetic field. The transmitter coil is supported by a generally rigid transmitter frame. The transmitter frame comprises a plurality of frame sections assembled in a way such that the generally rigid transmitter frame substantially retains a rigid shape during operation. The system may also include a receiver section located above the generally rigid transmitter frame in between the aircraft and the generally rigid transmitter frame for detecting the secondary electromagnetic field.