On-Ground Small LTCC Chip Antenna and its Placement on IoT Devices

A low-profile on-ground chip antenna is presented to be installed in size-limited devices for 868 MHz Internet of Things applications. The antenna presents a size of 0.064
$\times\, 0.045\,\times\, 0.007\lambda _{0}^{3}$
, has been fabricated in low-temperature cofired ceramic technology, and is meant to be placed on a ground plane without a clearance area required. A study regarding matching and total efficiency is performed by analyzing the antenna in different positions of a variable-size ground plane with the use of characteristic modes analysis and the correlation between modal and total radiated fields. The analysis demonstrates through the correlation which are the excited modes of the ground plane and, consequently, which is the best position for the antenna. Results show frequency stability and a total efficiency difference of up to 8.8 dB between different positions.