First Experimental Results with the Imaging MIMO Radar MIRA-CLE X

MIMO radar for imaging is a quite new and promising research field with a big potential for various applications. Three different imaging radars based on the MIMO principle are currently developed at Fraunhofer FHR. This paper describes the ground based X-band MIMO radar MIRA-CLE X. This radar consists of 16 transmit and 14 receive antennas which are arranged in a special way to synthesize a fully and equally spaced virtual antenna array of 224 elements during signal processing. First image results of MIRA-CLE X are presented and discussed. 1 Imaging MIMO Radar Imaging MIMO radar systems using colocated transmit and receive antennas are the keys to various new and promising applications, like environmental monitoring, security surveillance, and assistance systems. For a coherent MIMO radar, NTX transmit (TX) and NRX receive (RX) antennas are placed in a particular way (ARTINO1 principle) in order to form a fully distributed antenna array of NTX ×NRX virtual elements during signal processing [1] [2]. The virtual antenna elements are located at the centers of gravity between the phase centers of each TX/RX pair (see Figure 1). Figure 1: Arrangement of TX and RX antennas according to the ARTINO principle. Three different imaging MIMO radar demonstrators are presently developed at Fraunhofer FHR. The first one is the airborne radar ARTINO which consists of a small UAV with an integrated MIMO antenna in the wings operating in Ka-band. It allows to image the directly overflown scene in three dimensions [3]. The second radar demonstrator is the ground based Ka-band MIMO radar MIRA-CLE2 which generates in the basic configuration 256 virtual antenna elements [4]. A main feature of this system is the potential to use waveformand frequency diversity to increase the SNR and to allow a high PRF [5]. A reasonably high PRF is necessary for instance to image non stationary objects. The third MIMO radar is the X-band system MIRA-CLE X which is presented in this paper. 2 System Specifications Figure 2: MIRA-CLE X: Superposition of the antenna image with the schematic diagram. In the shown MIMO configuration, only a sparse set of patch antennas of the receive antenna is used. The idea of MIRA-CLE X was to develop a quite costefficient X-band MIMO radar made of already available components. The array antenna of MIRA-CLE X has a length of about 2 m (see Figure 2). The experimental setup consists of the switching matrix, the signal generation, and the receiver followed by an acquisition unit. The system works at a center frequency of 9.45 GHz and has an instantaneous bandwidth of 1 GHz. The base band signal is generated by an arbitrary waveform generator, mixed upwards to X-band, and amplified. The radiated pulse power amounts to 33 dBm. The expandable and reconfigurable construction allows easily to use more powerful amplifiers for long distance applications. A switching matrix consisting of fast pin diode switches operates the sequential distribution of the transmit and receive power, controlled by a 48-channel pattern generator. The data acquisition is 1Airborne Radar for Three-dimensional Imaging and Nadir Observation 2MIMO Radar Configurable EUSAR 2010