A planar miniaturized branch-line coupler with harmonic suppression property for UHF band applications is presented in this paper. By properly synthesizing the LC-tanks that employ artificial transmission lines, two pairs of quarter-wavelength branch-lines to respectively meet characteristic impedances of 35.4 and 50 ohms can be obtained with the coupler. For the operating band, it can achieve good 3dB power division with a 90° phase difference in the outputs of the through and coupled arms. The coupler also has a small area of 20.5(L) × 18(W)mm², corresponding to 0.11λg×0.1λg at 922MHz. Compared with conventional couplers, the proposed design not only offers a wide bandwidth of more than 230MHz within ±1° or ±1dB, but also works with additional harmonic suppression for achieving better performance. Therefore, the proposed branch-line coupler with a compact size is well suitable for power division application.