Multiport Multiband Chassis-Mode Antenna Design Using Characteristic Modes

Multiport antenna architectures that are well isolated, both within and across multiple frequency bands, not only support multiple technologies such as multiple-input--multiple-output and carrier aggregation, but also ease the design of the RF front end. In this letter, the theory of characteristic modes (TCM) is applied in a systematic manner to isolate the ports operating in the same frequency band and in different frequency bands, the latter of which is a new application of TCM. Moreover, by quantifying the amount of isolation between the multiple ports via the electromagnetic isolation method, the use of TCM as a decoupling tool for multiple antenna systems is verified. A four-port chassis-mode antenna is presented that features high levels of interband and intraband decoupling in three bands, two of which are below 1 GHz. The antenna is experimentally verified, and the measured port parameters and radiation patterns are found to match well with simulations.