In tuning an antenna, there are multiple possible topologies that will take it to the middle of the smith chart.

Some differences that I can see between them are:

  • Component ESR (losses).
  • Effect of component tolerances.
  • Resulting antenna bandwidth.

For example:

Alternative 1 "LpCs"

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Alternative 2 "LpLs"

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Alternative 3 "LsCp"

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Which one would you choose and why?

  • \$\begingroup\$ Too broad - ask a more realistic question that doesn't require anyone answering to consider a million combinations of this and that in order to possibly satisfy the problem you have in mind. \$\endgroup\$ – Andy aka Aug 21 '14 at 20:08
  • \$\begingroup\$ @Andyaka Oh my God, really Andy? This is a perfectly realistic question, and extremely narrow. In fact, it is partially answered in the beginning of it. If you need more information, just ask for it. Surely it isn't 'a million' things. \$\endgroup\$ – apalopohapa Aug 21 '14 at 20:22
  • \$\begingroup\$ As you say in your question "there are multiple topologies" so don't act all innocent on me. If you want a question answered properly don't expect a thesis or an essay. \$\endgroup\$ – Andy aka Aug 21 '14 at 20:36
  • 3
    \$\begingroup\$ @Andyaka The question is specific about choosing between exactly 3 different alternatives. I think it is useful and interesting to come up with criteria about how one goes about choosing one. An essay would be very generous, but not in the least expected. A few bullet points would suffice. An example based on experience would be great. \$\endgroup\$ – apalopohapa Aug 21 '14 at 20:53
  • 2
    \$\begingroup\$ I am too very interested in the possible answers to this question. \$\endgroup\$ – Guillermo Prandi Aug 22 '14 at 22:32

Versions 2 and 3 offer a DC path to the antenna. If your antenna is a HF long wire, your protection from lightning strikes is not too good.
Smith charts imply you are talking UHF / microwave: antennas are smaller, lightning strikes are less common. If you have some form of masthead amplifier, you may actually want a DC feed.
Unless this is the case, I'd stick with version 1.


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