Dipole Antenna With Both Odd and Even Modes Excited and Tuned

Dipole antenna is the simplest type of antenna from the theoretical point of view. However, the majority of the research on it focuses on adding supplementary structures to produce more resonant modes to achieve more functions. Here, we focus on the inherent modes of the dipole itself. Dipole antenna has alternating odd and even modes. In classical antenna theory, only odd modes are excited. The even modes are difficult to be excited due to their very high input impedances. In this article, both odd and even modes of the dipole antenna are excited simultaneously by a single port with a novel feeding structure. Moreover, to tune the resonant frequencies of such multiple modes, a method by combining antithetical structures of indentations and outdentations is proposed. Its principle is explained intuitively by eigencurrent distribution. By these new techniques, all the first six modes of a dipole are excited, among which five modes are used for Internet of Things (IoT) applications. The antenna can cover industrial, scientific, and medical (ISM) bands of 868 and 2450 MHz, global navigation satellite system (GNSS) band of 1575 MHz, and 5G bands of 3500 and 4900 MHz. This research could broaden the application of this classic antenna.