In a four ports hybrid coupler the rate and phase between the output and
coupled port is fixed.
The fourth terminated port serves to absorb the energy that's not
dissipated, or by the main output load and/or by the coupled port load.
When the output port and the coupled ports are terminated to the proper load
no current flows in the termination and things are ideal.
Althought an hybrid coupler is unable to force energy to flow toward a
mismatched load, phase is anyway kept.
When the match exist and a 0 or 180 phase shift is convenient, through a
proper LC external circuit that matches and further adjust phases to the
required value (i.e 90°), it's possible to use an hybryd coupler as a power
splitter.
Basically, the advantage could be that an hybrid coupler is a broadband
device that can be used, togheter its switching system, for more than a
single band antenna system.
73,
Mauri I4JMY
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