A Half-Cut Compact Monopole Antenna for SFCW Radar-Based Concrete Wall Monitoring with a Passive Cooperative Target

Stepped frequency continuous wave (SFCW)-based radar with passive cooperative target is a promising nondestructive method to monitor the concrete temperature change. By burying a surface acoustic wave (SAW) sensor in the concrete to act as the cooperative target, the physical properties of the concrete can be measured by analyzing the reflections of the probing SFCW signal. Because the SAW sensor should be connected to an antenna to convert the electromagnetic wave into the acoustic wave, a half-cut compact monopole antenna is designed and fabricated in this letter. Taking the advantages of corrugated edge and half-structure technologies, the size of the monopole antenna decreases significantly without sacrificing the performance, which makes the SAW sensor together with antenna suitable to be inserted into the concrete. The experimental results show that the proposed antenna can work well with the SAW sensor in the concrete and the proposed method can measure the temperature change in concrete continuously.