  Quantum sensing using local defects in solid-state systems has gained
significant attention over the past several years, with impressive results
demonstrated both in Academia and in Industry. Specifically, employing large
volume and high density ensembles for beyond state-of-the-art sensitives is of
clear interest. A major obstacle for achieving such record sensitivities is
associated with the need to realize strong, homogeneous driving of the sensor
defects. Here we focus on high-frequency microwave sensing using
nitrogen-vacancy centers in diamond, and develop a modified split-ring
resonator design to address this issue. We demonstrate enhanced drive strengths
and homogeneities over large volumes compared to previous results, with
prospects for enabling the desired sensitivities. We reach Rabi frequencies of
up to 18 [MHz] with an efficiency ratio of 2 [$Gauss/\sqrt{Watt}$], along with
an inhomogeneity of $<0.7\%$ in a volume of $0.1\:mm^3$.
