How to convert RF balanced output to unbalanced with improved harmonics level?

Usually there is an inductance providing 180deg shift and capacitor to make low-pass filter to stop harmonics.
But what if we need harmonics? I think 180 deg shift must be turned off, then two diodes added in such way, that each line of balanced output gives 50% sine, and as a result - unbalanced output with second harmonic. Is that right?

Look at a bridge rectifier, earth the DC- terminal output is DC+ terminal. feed each AC terminal with a sine wave which is anti phase, so get your signal source and split it into a +90 and a -90 degree signal and feed the AC terminals. Select diodes for working at output frequency.
frank

What about higher harmonics, does balanced output have any advantages to get the third harmonic? I think there is a way to play with phase and maximise output, but not sure yet how to calculate it.

What frequency you working at? Is it CW?

LO is about 2GHz, 0dBm. Idea is to try N multiplication without using additional amplification stages. I read about varactor multipliers are good efficiency, but diffictult to design for good performance.

@CW: Yup, non-linear devices (unless they are amplifiers) in an RF path at this frequency can be detrimental to the signal integrity.