In this paper, chromatic fiber-dispersion effects are studied in a radio-over-fiber (RoF) system with optical phase modulation and coherent detection at 60, 75 and 100 GHz using binary and quaternary phase-shift-keying (PSK) modulation over 40 and 80 km of single-mode-fiber. Electrical spectrum at the receiver and constellation diagrams are analyzed, and the bit error rate (BER) are calculated varying the signal to noise ratio (SNR), reaching a successful transmission below 17 dB in QPSK and 12 dB in BPSK of SNR for a 1 Gbps, showing in BPSK transmissions similar BER using different carrier-frequency. In QPSK transmission the influence of higher carrier-frequency is noted with BER increasing.