UTEM Mk3 Transmitter

Geophysics Collection · Physics

Accession Number: 2019.ph.838

Description:

A grey enclosure with a removable front lid. The case has a handle at one side. The lid has two removable hinges at one edge and two latches at the other. There are four small black rubber feet on one side of the case.

Under the lid is a console with several switches, dials, jacks, and other elements. These include a standard AC plug.

Primary Materials: Metal, Plastic.

Markings:

A number of settings and values are written on the inside surface of the lid in black ink, green ink, and pencil. This information is challenging to transcribe but is legible in the appended photos. This information includes the instrument’s weight (40 lbs).

Some information has been added to dials and other locations on the console. This writing is illegible because the tape covering it has yellowed.

Dimensions (cm):

Height = 24, Width = 44.5, Length = 28.8.

Function:

The UTEM Mk3 was part of a ground-based apparatus used to prospect for economic minerals using transient electromagnetic (TEM) technology.

TEM creates and detects induced fields in conductive minerals. The transmitter was used to transmit an electrical signal through a long wire loop. This signal was then detected using a mobile receiver system.

The Mk3 and later versions could also be used with an axial borehole probe system.

Condition:

Good: The outer case is worn and scuffed, with old adhesive visible in various places.

Manufacturer:

University of Toronto Department of Physics

Provenance:

This instrument was built at the University of Toronto Department of Physics. It was acquired by Lamontagne Geophysics Ltd. (formerly in Toronto, now in Kingston, Ontario).

It was returned to the University of Toronto Department of Physics, and donated to the University of Toronto science collection on July 22, 2019.

Additional Information and References:

Lamontagne, Y., & University of Toronto. (1975). Applications of wideband, time domain, EM measurements in mineral exploration. Doctoral thesis, University of Toronto.

West, G. F., Macnae, J. C. and Lamontagne, Y. (1984). “A time-domain electromagnetic system measuring the step response of the ground.” Geophysics 49, 1010-26.

Historical Notes:

A document prepared by Dr. Yves Lamontagne, President of Lamontagne Geophysics, Ltd. on 19 July 2019 includes the following information:

UTEM Mk3 Transmitter

This was the third transmitter prototype. The first transmitter was a one-sided current regulating transmitter with a similar time base as the receiver and peak voltages of +/-140V. The output waveform was an exact ramp. It was in a grey case of cuboid shape and may still be at U. of T.

There is a photo of it in my thesis. The second transmitter (UTEM II) was built by Geonics as part of the WBTD and then heavily modified by me to stabilize its operation when driving a realistic inductive loop. It was packaged in an orange colour case with additional circuitry such that the lid could not be closed. It may also still be at U. of T.

The UTEM Mk3 transmitter was built later in the WBTD project prior to a series of more demanding field surveys. This transmitter was optimized for use with larger loops. It featured higher power, the use of switch-mode regulated power supplies and differential drive output producing a much higher peak output voltage swing of +/- 285V and peak current of 5A.

UTEM is a ground-based (as opposed to aircraft based) transient electromagnetic system (TEM). Electromagnetic prospecting technologies emerged after the Second World War in Canada and Scandinavia, where generally resistive environments made them practicable.

TEM systems were an evolution of the earlier electromagnetic prospecting systems that took advantages of advances in electronics in order to apply the technology to more challenging environments while producing more interpretable data. The purpose of the UTEM project at the University of Toronto was to “measure directly the magnetic and electric fields induced by a fixed transmitter system in the ground over a relatively wide band of frequencies.” [Lamontagne 1975, 5]

The UTEM system uses a generator-driven transmitter coil to induce a secondary (transient) field in conductive minerals. These transients are detected and recorded using a mobile receiver coil and meter.

The UTEM system was developed by Dr. Yves Lamontagne and his graduate supervisor, Professor Gordon F. West, at the Geophysics Laboratory of the University of Toronto. The system was meant to be readily adaptable to commercial surveys. Dr. Lamontagne completed his thesis in 1975. In 1979, he established the Lamontagne Geophysics in Toronto, Ontario. In 1990, the company moved to Kingston, Ontario.

The UTEM system has gone through several generations. It has assisted in the discovery and investigation of mineral deposits around the world, including an important deposit in the Sudbury nickel area.

  • Donated to UTSIC