Aerospace and Electronic Systems Magazine April 2018 - 47

advantages of having a radar and a camera for object classification
is presented in [6]. This system, as well as the others, does not create a full 3D reconstruction of the observed scene. Moreover, the
chosen camera has a low resolution, which can be appropriate in
an automotive context, but not for medium-range applications. The
advantages of having a multifunctional system in a naval environment are well described in [12]. In [8], a sensor fusion system,
which uses a combination of a light detection and ranging, radar,
and a camera in the automotive context, is presented. Here, the focus is on a learning system for detection and classification of road
obstacles, not hardware-related details.
In this article, a 3D FMCW MIMO radar, in combination with
a camera and a two-axis gimbal, placed in the center of the MIMO
array, is presented. For a determined number of transmit (TX) and
receive (RX) modules, a MIMO radar offers higher angular resolution compared to a conventional phased array radar [13]. Consequently, it is smaller, is lighter, and costs less. The MIMO architecture uses the spatial separation of the antennas to create a so-called
virtual array, which can be calculated via a discrete convolution
[14]. The size of the resulting virtual array, not the physical array,
determines the angular resolution of the MIMO radar system. If the
TX and RX antennas of the array are placed in a rectangular configuration, the center of the antenna aperture is unoccupied. This
area is used to place the camera and the gimbal (Figure 1). With the
gimbal, it is possible to steer the camera to the target detected by
the radar. The antenna board consists of 16 TX and 16 RX antennas. The radar operates in the frequency band from 16 to 17 GHz
(Ku band), with an operational bandwidth of 1 GHz. TX signal orthogonality is achieved by employing a time domain multiplexing
(TDM) strategy. A 3D-printed housing that protects the circuitry
and acts as a cooling system for the electronic has been fabricated
and assembled.
APRIL 2018

The target application of the multifunctional 3D FMCW
MIMO radar is ground-based surveillance of stationary wide
zones and infrastructures, such as high-security or hazardous areas.
These could be chemical or nuclear power plants, energy transmission infrastructure, fuel pipelines, and several other applications in
which a compact and easily deployable platform is highly desired.

SYSTEM ARCHITECTURE
The top-level system architecture of the MIMO radar demonstrator
is presented in the form of a block diagram in Figure 2. The main
components are the antenna board, the digital board, the direct digital synthesis (DDS) board, the receiver, the laptop, and the camera. The modular approach of the 3D-printed housing easily allows
addition and change of hardware components. The following text
describes the block diagram and explains how the system works.

Figure 1.

Visualization of a rectangular MIMO array with unoccupied space in the
center (left) and a camera (right).

IEEE A&E SYSTEMS MAGAZINE

Table of Contents for the Digital Edition of Aerospace and Electronic Systems Magazine April 2018