Two new photonics-based microwave frequency translators are presented. They are based on Serrodyne modulation to frequency translate an optical carrier, which beats with a microwave signal sideband at a photodetector to generate a frequency translated microwave signal. The proposed frequency translators have a simple structure, a wide bandwidth and a large spurious signal suppression ratio. Experimental results are presented for the novel structures, which demonstrate the realisation of microwave signal frequency translation with >38 dB spurious signal suppression over a wide microwave signal frequency range of 2 to 18 GHz and with >35 dB spurious signal suppression for a translation rate of 500 Hz to 3 MHz. Frequency translation of an 80 MHz bandwidth frequency modulated continuous wave signal at 5.88 GHz frequency with >34 dB spurious signal suppression is also demonstrated.