As a point of reference, a typical NE3508M04
(http://www.cel.com/pdf/datasheets/ne3508m04.pdf) can give you a device
noise figure under 0.4dB, operated at room temperature, at any
frequency across the entire "UHF" frequency range (300MHz to
3GHz)--better than that at the lower end of the frequency range.

Cheers,
Tom