Constructive interference in radiowave propagation
"Cecil Moore"
Still there are those nagging assertions of Born
and Wolf that for two equal magnitude signals,
the total intensity possible for incoherent
signals is double the intensity of one signal.
The total intensity possible for coherent
signals is four times the intensity of one signal.
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It is a fairly common practice in broadcast designs to combine the outputs
of two r-f amplifiers of equal power rating, using a 4-port, 3 dB coaxial
hybrid. The two amplifiers are driven by a single exciter through a
suitable splitter. The antenna connects to one output port of the hybrid,
and the other output port is connected to a dummy load.
When the relative r-f phases of the two txs are suitably set, the antenna
connection of the hybrid receives the total output power of the two txs, and
the dummy load port receives zero. When the relative r-f phases of the txs
are changed by 90 degrees from that setting, then the conditions at the
output ports are reversed.
The total average power available at the hybrid output for both of these
conditions is twice that of a single tx without the hybrid.
Does the quote from Born and Wolf support this?
RF
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