Multi-band Dipole Antenna by Multi-mode Excitation for Massive Connections of IoT

The Internet of Things (IoT) develops rapidly at present and in the foreseeable future. A fast-increasing number of devices are being connected wirelessly. This connectivity is provided by different wireless technologies operating at different frequencies. Thus, future wireless smart devices should have the ability of massive IoT connections, and their antennas need to cover multiple frequency bands. This paper introduces two novel methods for linear-shaped multi-band dipole antennas for small wireless smart devices, such as strip- or bar-shaped AR/VR smart glasses, smart wristbands, smartwatches, smart pencils. The analysis is based on the theory of characteristic modes. First, we know a classic dipole antenna resonates only at odd modes, limiting the design of multiple frequency bands. Thus, a novel feeding structure is introduced to excite both odd and even modes of a dipole antenna simultaneously. A flexible method is also introduced to pick out and tune specific mode(s) among them. Second, we introduce an algorithm to calculate the fewest arms required by a multi-arm linear dipole antenna. By these two novel techniques, antenna designers could realize multi-band antenna more easily on narrow surfaces.