An embeddable microwave patch antenna module for civil engineering applications

In this paper the design and the results of the investigation into the performance of an embeddable antenna module for civil engineering applications are presented. The module consists of a rectangular microstrip patch antenna, a microstrip inset feed, electronic components such as a rectifier circuit and a protective housing. The housing is used to protect the antenna, the feed and the electronic components from the physical, chemical and electromagnetic influence of the surrounding material. First, a conventional transmitting mode approach is used to analyze and optimize the antenna to operate at ~2.5 GHz when embedded in concrete. Then, a receiving mode approach is used to investigate the performance of the embedded antenna module for two different external sources of excitation; namely, a plane wave and a second antenna in free space. It has been shown that by choosing the appropriate dimensions and dielectric property of the housing, the influence of the concrete on the resonant frequency and the magnitude of the reflection coefficient has been reduced. The feasibility of the embedded antenna module along with a rectifier circuit for a wireless microwave power transmission inside concrete has been demonstrated. The simulation and measurement results obtained with early-age concrete mimicking substance using two-antenna setup are in good agreement. The antenna module can be used for wireless power transmission through building materials such as concrete and for material characterization.