This paper presents an experimental investigation of two approaches to short-range radar imaging at microwaves by means of ultra-wideband (UWB) technology. The first approach represents a classical synthetic aperture radar (SAR) that employs a transmit¿receive antenna pair on mechanical scanner. The second one makes use of a multiple input multiple output (MIMO) antenna array that scans electronically in the horizontal plane and mechanically, installed on the scanner, in the vertical plane. The mechanical scanning in only one direction reduces significantly the measurement time. Two respective prototypes have been built and compared. Both systems comprise the same 10¿18 GHz antennas and multi-channel video impulse electronics while the same data processing and imaging method based on Kirchhoff migration is applied to acquired data for digital beamforming. The study has been done for an application of concealed weapon detection.@en

Two Ku-band antenna elements to be used in full-polarimetric UWB arrays are introduced. Both antenna elements consist of four linearly polarized UWB radiators. It is demonstrated that both elements have over 100% fractional bandwidth, good impedance matching, linear phase (almost constant group delay) and uni-directional patterns.@en

In this paper two setups to measure the return loss, radiation patterns, and antenna gain for mm-wave differentially fed antennas are proposed and tested on a Ka-band LTCC antenna. The first measurement setup uses a dedicated CPS to microstrip line transition keeping differential antenna feeding. In the second measurement setup a specially designed balun is used to feed the antenna. For both measurement setups several TRL calibration standards to de-embed the effects of the feeding structure are designed. Calibration procedure for the radiation patterns by using a reference antenna is proposed.@en

In this paper two novel MIMO UWB antenna arrays have been proposed for through dress imaging radar application. The advantage os using MIMO array is that the number of elements can be reduced and the element spacing can be sparser than that of SIMO array, while the performance will be almost the same. Particle swarm optimization (PSO) method is used to determine the optimum antenna array topologies for different scenarios that can provide sufficient cross-range resolution and an acceptable mainlobe to side lobe level. The results demonstrated that by properly design the fitness function, we can trade off the cross-range resolution and mainlobe to sidelobe ratio and find proper array topologies for different scenarios.@en