开云体育

A nice document with a lot of good information.? The restrictions on impedance matching range in Figures 4 and 5 of the Abracon white paper are shown in more detail in Figures 5.57 and 5.58 of the 2021 ARRL Handbook and in similar figures in earlier editions.

Note that the restriction on the geometry of L-networks (Rs < Rl) in Figure 5.58 applies to all combinations of impedances only when the impedances on both sides are real.? The impedances on either side may be complex in practical installations, especially when electrically short antennas are to be matched.

Figure 5.58 of the Handbook shows only two L-network geometries that conform to the restriction, both of which place the parallel element across the higher of the two impedances.? For some combinations of impedances, it is possible to reverse the network, yielding four possible geometries instead of two.? In "More Octave for L-Networks," QEX, May/Jun, 2012, a GNU Octave procedure is given for determining whether or not an L-network may be reversed and, if so, what other geometries result from that reversal.? The Octave code gives values for the elements of either two or four L-networks as appropriate.

73,

Maynard Wright
W6PAP