We propose highly transparent (optical transmittance 92.7 % at 550 nm) single-layer bandpass filter operating in dual frequency bands of 26 and 38 GHz for 5G communication systems. The dual-band bandpass filter achieves not only high optical transparency but good electrical performance. The transmission performance of the filter is stable to the polarization and incidence angle of electromagnetic waves. As a proof of concept, we fabricate a filter with periodic square loops patterned on 188 μm-thick substrate, and each loop is realized with metallic mesh electrodes having a pitch of 10 μm. Measurements are conducted using two different measurement systems; a free-space measurement system and a vector network analyser-based material characterization kit. After calibrating the measurement system, the scattering parameters of the filter are measured. The measured results obtained using the two systems showed good agreement and also agree with the simulated ones. The designed filter has insertion loss of less than 3 dB in the dual passband region.