Abstract
Abstract
This work presents a wideband millimeter-wave (mmWave) antenna designed and experimentally validated using the Characteristic Mode Theory (CMT). The proposed single-element is implemented on an ultra-thin 0.254 mm substrate and occupies a compact footprint of 8 × 6 mm
2
. The antenna achieves a wide impedance bandwidth from 22.5 to 39 GHz, corresponding to a fractional bandwidth of 53.66%, covering the major 28 GHz and 38 GHz 5G mmWave bands. CMT analysis is employed to investigate the dominant electric-dipole modes across various frequency bands. Further, by keeping the ground length constant at
$$0.3{\lambda}_{0}$$
, the monople structure is varied to suppress the magnetic-dipole modes, thereby improving the linear polarization behavior with electric-dipole modes. The CMT for the proposed single-element structure illustrates that modes
$${J}_{3}+{J}_{1}+{J}_{4}$$
,
$${J}_{3}+{J}_{4}+{J}_{5}$$
,
$${J}_{3}+{J}_{2}+{J}_{4}$$
, and
$${J}_{2}+{J}_{3}+{J}_{5}$$
are contributing to resonance at 24, 28, 32, and 36 GHz, where the first modes in each band indicate the dominant mode with relatively higher magnitude. The summation of these multiple excited modes across multiple bands has led to a wideband resonance with a stable radiation pattern. To improve the radiation performance for high-gain mmWave applications, the optimized single element is extended into a 1 × 8 linear array configuration. The proposed array achieves a gain variation from 11 to 15.8 dBi across the operating band, with peak gains of 12.8 dBi at 28 GHz and 15.5 dBi at 38 GHz. The measured results obtained from the developed prototype show good agreement with the simulated responses, validating the proposed CMT-guided design approach. Due to its compact size, ultra-thin profile, wide bandwidth, high-gain array performance, and clear modal interpretation, the proposed antenna is a promising candidate for future 5G mmWave wireless communication systems.