Table 5: Techniques for DRAs excitation.

Feeding techniqueCharacteristicsReference

WaveguideHigh coupling with high permittivities DRAs achieved through a slot in the waveguide wall.[171173]

Aperture coupledUsed to excite a DRA using a microstrip line (a reduced surface waves level is excited).[174178]

Microstrip lineUsed to excite high permittivity DRAs. For low permittivity DRAs, tall microstrip lines (TMLs) with a dielectric support are used to enhance the coupling [115, 179].[179181]

Electric probeUsed to excite a DRA using a coaxial cable.[182187]

Strip-fedUsed to excite a DRA when broadband antenna behavior needs to be achieved.[188190]