Here is an image of the AN/MPQ 501 and the final mounting configuration with the modifications to the upper hull of the M113A1CDN. This is not the photograph used in my Service Publications WoW book on the M113A1CDN nor my article in IMPS RT but gives a better view of the top hull.
Prior to the introduction of the M113A1CDN by the Canadian military the AN/MPQ 501 was intended to be mounted on the Bobcat and here is a concept photograph of that configuration.
COUNTER-MORTAR RADAR AN/MPQ-501
This Counter-Mortar Radar equipment was developed for the Canadian Army by the National Research Council and was production-engineered and produced by Raytheon Canada Limited. The AN/MPQ-501 equipment was a mobile microwave radar for the field forces designed to locate the source of hostile mortars, rockets, and other high-angle artillery. It also had demonstrated an ability to locate field artillery and provide rapid registration of counter gunfire. Designed for mounting on an armoured vehicle of the M113 and other types, the radar had a high degree of mobility, enabling it to move rapidly to site, perform its function, and then quickly move away. The air transportability of this equipment, when mounted on such an armoured vehicle, had been demonstrated by the RCAF when they transported tactical vehicular installations of this radar equipment non-stop to Europe from the RCAF Downsview airport in a C130 Hercules.
The AN/ MPQ-501 would perform the following functions:-
(a) Accurate location of hostile mortars and other high-angle artillery.
(b) Registration and adjustment of divisional artillery.
(c) Location of hostile ballistic rocket positions.
(d) Combat area surveillance.
(e) Survey of own and other positions.
Outstanding features of Radar AN/ MPQ-501
• 5 minutes into action and 2 minutes out of action-day or night.
• One man setup and operation without exposure.
• Fully automatic antenna levelling.
• Automatic loading and stowage.
• Automatic time insertion, beam centering and shifting.
• First round location.
• Simultaneous fire capabilities.
• True presentation of signal pairs to avoid confusion.
• Single beam extrapolation provided.
• Locations in both Cartesian and polar co-ordinates.
• Fall of shot corrections direct on counters.
• Fast automatic computer clearing between rounds.
• No trailer, no field cables-self-contained and powered on single armoured
vehicle allowing maximum mobility.
• Fully air-conditioned including N.B.C. protection.
• Frequency, power, noise figure and tuning monitored.
Raytheon Canada Limited was equipped to design, develop, and manufacture
high quality radar systems such as the AN/ MPQ-501, as well as communications radar equipment for airport and airways surveillance.