Zehlendorf MW flared skirt antenna and diplexer   3EN
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MW antenna Zehlendorf 603 kHz (50 kW) und 693 kHz (250 kW)
The photo shows the inflexion point of the flared skirt (cage). There is a long rod insulator at the top of the guy which keeps the flare skirt in its position.
MW antenna Zehlendorf diplexer design
The two frequencies 603 kHz (50 kW) and 693 kHz (250 kW) are very narrow. Because of this and the high powers the coils and capacitors become very large.
Both branches of the diplexer contain one rejecton filter (trap circuit) and one absorbtion circuit for the second frequency.
In addition a trap circuit of 177 kHz was provided, because this frequency is radiated from a neighbouring mast of 362 m  on the same antenna site.
Antenna impedance
Convenient impedences at the base of the antenna.
Measured figures
603 kHz: Impedances at the input of the diplexer, measured at  the cable of 50 ohms.
Measured impedances  for 603 kHz from
+13.8 kHz to - 18.45 kHz at the cable

The outer circle of the Smith- Chart corresponds to the standing wave ratio of  s= 1.5.
693 kHz: Impedances at the exit of the diplexer, measured at  the cable of 50 ohms.
Measured impedances  for 693 kHz from
+57.0 kHz to - 15.75 kHz at the cable

The outer circle of the Smith- Chart corresponds to the standing wave ratio of  s= 1.5.
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