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 == Antenna impedance matching ==
-TODO
+Different antenna types have different ideal input impedances. And, the the input impedance is typically frequency dependent. For instance, a given antenna may look like a 50 ohm impedance at 5 MHz, but may look more like an open circuit at 10 MHz.
+Example: the ideal dipole antenna has a 73 ohm input impedance. Feeding this antenna with a coaxial cable of 50 ohm characteristic impedance, leads to a 50 ohm -> 73 ohm impedance interconnect. This impedance difference will result in signal reflections, which are unwanted for several reasons.
+Overcoming impedance differences in antennas may for instance be done using matching networks.
+Matching an antenna gets harder as the operational band of the antenna grows larger.