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A slim and semi-flexible UHF RFID tag antenna, which has a compact dimension of 40 mm $\times $ 5 mm $\times $ 3.2 mm ( $0.1221\lambda \times 0.0153\lambda \times 0.0098\lambda $ ), is proposed for tagging on metallic industrial tools with a narrow footprint. For a metal-mountable tag antenna, the unwanted electromagnetic antenna-metal interaction can deteriorate the tag read performances and it is particularly pronounced when the tag is attached to a narrow industrial tool. To achieve a size-reduction, the proposed tag is made of an inlay comprising a very compact 3-layer structure with two radiating patches. The currents on the top and middle patches can be made in phase for enhancing the radiated fields. Digital serrations, inductive stubs, and open slots loading have been studied for optimizing the antenna resonant frequency efficiently. With the use of the tuning mechanisms, when being tested on a narrow-body metal tool, the antenna impedance can be fully matched with the RFID microchip impedance, resulting in a good power transmission coefficient of ~ 1. Despite its compactness, the proposed tag antenna is readable from 11.0 m with an EIRP of 4W. To the best of our knowledge, the proposed tag antenna has a much better aspect ratio between its read distance and tag volume than most of the commercially available on-metal tags and it can be used for tagging on narrow metallic surfaces.

A highly miniaturized semi-flexible tag antenna, with dimensions 23 mm $\times \,\, 7.5$ mm $\times \,\, 3.2$ mm ( $0.0702\lambda \times 0.0229\lambda \times 0.0098\lambda $ ), is designed for tagging small metallic objects. It consists of three patches and two foams which are tactfully folded to form a very compact three-layer structure. Multiple slots are etched on the top and middle patches for increasing the current paths, where the slots on the top patch are made orthogonal to those in the middle one so that the currents on the two patches do not affect each other. This enables the currents on the two patches to be tuned independently without affecting the tag performances. Despite its small size, the proposed tag is able to generate sufficient antenna resistance to match the impedance of the microchip. As a result, it is able to achieve a good conjugate match with a power transmission coefficient of ~1. The tag has a very compact size of $\sim \lambda $ /14. It can be read from a distance of 5.0 m when tested on a metal surface with reference to a transmitted power of 4 W effective isotropic radiated power. To the best of our knowledge, as compared to most of the contemporary tags, this is the best performing tag antenna in terms of size-ratio (read distance/tag volume).

In this paper, an innovative type of smart antenna based on genetic algorithm (GA) has been developed and tested. The new GA embedded solution simplifies the control of smart antenna system with increment of the accuracy of beam coverage and decrement of beam availability in compare with the conventional switch beam smart antenna. Scanning antenna of the system determined the location of mobile users through its band passed radio frequency power detector circuitry. GA then operates to optimize and steer the coverage beams to cater for dynamic users' distribution with minimum power usage. The experiment with GA embedded control system smart antenna shows good result in beam formation and steering to handle mobile users.