ADL5801 RF Input Matching


I am using the ADL5801 as a UHF->IF converter. The chip's datasheet shows on fig.21 page 11 the RF port return loss. The first half of UHF band is poor since it begins at -5 down to -10 dB. There are no information concerning the S11 matching in the UHF band in the datasheet.

How can i improve the S11 of the RF port in UHF band ?

Thanks in advance to those who can help