Why we use 50MHz as a reference?

Hi,

Why in measuring RF power, a commonly used reference is 50MHz? Why not 100MHz or 60MHz or 55MHz?

Thanks.

this is the HP's hobby and now it became a standard

It is related to efficiency of the RF system.

For 50Ohm, it is balance the power efficiency in RF circuit and radiation efficiency in antenna.

see topic on https://www.edaboard.com/ftopic262097.html.

BR

Thanks for the replies, but I think the question is why 50MHz instead of why 50 Ohms.

in architecture such as integer-n fhss (i.e. bluetooth), Fref must be equal to channel spacing (i.e. 1MHz), right?

(how) does this requirement differ for fractional n Σ-Δ?