New Concept of Combined Microwave Delay Lines for Noise Radar-Based Remote Sensors

Abstract

Delay lines with a tunable length are used in a number of applications in the field of microwave techniques. The digitally-controlled analogue wideband delay line is particularly useful in noise radar applications as a precise detector of movement. In order to perform coherent reception in the noise radar, a delay line with a variable delay value is required. To address this issue, this paper comprises a new concept of a digitally-controlled delay line with a set of fine distance gates. In the paper, a solution for micro-movement detection is proposed, which is based on direct signal processing in the time domain with the use of a microwave analogue correlator. This concept assumes the use of a microwave analogue tapped delay line structure. It was found that the optimal solution for a noise radar with an analogue signal correlator is a combined delay line consisting of switched reference sections, a tapped delay line, and a precision phase shifter. The combined delay line presented in this paper is dedicated to serving as the adjustable reference delay for a noise radar intended for the detection of micro-movement. The paper contains the calculation results and delay line implementation for a given example. The new structure of the analogue tapped delay line with the calculation of optimal parameters is also presented. The precise detector of movement can be successfully used for the remote sensing of human vital signs (especially through-the-wall), e.g., breathing and heart beating, with the simultaneous determination of position.

Bandpass NGD investigation of O-shape fully distributed structure with S-matrix modelling

“…The time-delay parameter is playing a capital role in the communication system in the different areas as in RF and microwave area (Wijenayake et al, 2012;Scalora et al, 1996;Condon et al, 2004). The delay effect can also be exploited to design different functions (Nabekawa and Midorikawa, 2004;Narasimhan et al, 2005;Vemagiri et al, 2007;Herrojo et al, 2019;Park et al, 2007;Szczepaniak and Susek, 2019). The group delay (GD) dispersion was exploited to design an indirect phase control mixer (Nabekawa and Midorikawa, 2004).…”

“…The transmission line (TL) delay was used to implement an RFID system (Vemagiri et al, 2007;Herrojo et al, 2019). Further, research works were conducted on the GD adjustment (Park et al, 2007;Szczepaniak and Susek, 2019;Song, 2008). Behind those classical exploitations of GDs, it was also found that the GD effect can be compensated by using the negative GD (NGD) function Broomfield and Everard, 2000;Meng et al, 2018;Shao et al, 2020).…”