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The dielectric characterization of concrete is a significant parameter to study the microwave signal transmission for the building materials. In this paper, a microwave measurement system has been developed using open ended coaxial sensor and vector network analyzer for frequency spectrum analysis of lightweight foamed concrete. The measurement setup is validated prior to make sure the system is working properly. The results of dielectric constant and loss factor of different densities lightweight concrete samples are measured and analyzed from 150 kHz to 8 GHz. From the analysis, the lightweight foamed concrete is a frequency spectrum friendly building material. In addition, the relationship between the dielectric constant and density of the lightweight foamed concrete is found to be interrelated. The empirical modeling of some selected frequencies has been formed. The models are useful for the future application on determining the dielectric constant and characteristic of lightweight concrete samples.

A simple and efficient variable optical attenuator (VOA) is achieved by using microbend gratings on single-mode fiber (SMF).The flatness of the attenuator is maintained for 100 nm along the CϩL band spectrum. Controlling the pressure will vary the attenuation depth of the device.

In this paper, a miniature folded dipole is proposed for designing a metal-mountable UHF RFID tag. The proposed tag antenna is low in profile and has a compact size of 40 mm × 40 mm × 3.1 mm (0.122λ × 0.122λ × 0.009λ). Folding the dipole arms into a twofold rotational symmetrical style can miniaturize the tag footprint for achieving high compactness. It has been found that the capacitive coupling mechanism between the rotational symmetrical radiating arms is effective in enhancing the vertical radiation, which subsequently improves the achievable read distance in the boresight direction. Also, an incorporated circular loop can provide additional inductance for achieving good impedance matching with the RFID chip. For the proposed tag antenna, a full ground plane is inserted underneath the radiator for isolating it from the backing metal, making the tag tolerant to the metallic platform. The proposed tag antenna is able to achieve a maximum read distance of 7 m at 4 W EIRP when it is tested on metal.