You can design the DC coupler like quarter-wave fingers. MOre fingers give a better RF response and lower DC voltage allowed. The DC block impedance should be close to 50 Ohms if this is line impedance. You can simply take a longer line length and using a razor cut two or more fingers in it to block DC. Keep fingers length the quarter wave, it works well.
To extend DC block bandwidth, cut finger length a bit longer and shorter than the quarter wave length, and cut more than two fingers. For higher DC voltages, use precut quarter-wave lengths of micro-coax rigid or semirigid cable, or find a SMD capacitor good for your frequency range.