A design approach to miniaturized, dual-resonant microstrip circular sector patch antenna with tilted circularly polarized (CP) beam is proposed. As mathematically laid down at first, the range of an asymmetric multiresonant prototype dipole's length should be set as the positive odd-integer multiples of one-quarter wavelength, such that the resonant frequency could be accordingly reduced by one-half to the symmetric case. In this way, an asymmetric circular sector patch radiator can then be employed to realize a unique tilted CP beam by simultaneously exciting two orthogonal, odd-order resonant modes via proper perturbations. As numerically and experimentally validated, dual-resonant microstrip antennas with compact patch, flared angles of 330°/270°, impedance bandwidth of 26.6%/35.8%, and tilted CP 3 dB axial ratio (AR) bandwidth of 7.3%/12.0% can be realized on single-layered, air substrate with a height no more than 0.07 wavelength. It is evidently verified that the proposed approach should be effective for reducing patch size, enhancing impedance bandwidth and realizing tilted CP beam without increasing antenna profile, inquiring multiple radiators or employing reactance compensation techniques.