I am new to antenna theory, and I have been reading up on antenna properties to create my own antenna.

I want to use a piece of copper wire, maybe around 18 gauge, as a monopole antenna, but it will also be electrically short, at least less than lambda/10.

Furthermore, the antenna will be designed for a single frequency.

Other than the fact that electrically short antennas have a high input reactance, I can't find any information on how to calculate the radiation resistance of a straight, round wire without using a network analyzer. Does anybody know of any information or software I could use to calculate this radiation resistance for impedance matching? Thanks!

  • \$\begingroup\$ This is beyond my own expertise, but I know that the ARRL Antenna Book (my copy is ancient) has not just a lot of theory, but also a lot of practical information on how to match impedances, check SWR, etc. arrl.org/shop/ARRL-Antenna-Book-22nd-Edition \$\endgroup\$ Sep 15, 2012 at 3:32
  • \$\begingroup\$ @mickeyf Thanks, I saw that the latest edition has chapters on space limited antennas and portable antennas. \$\endgroup\$
    – Ag565
    Sep 15, 2012 at 5:42
  • \$\begingroup\$ Do you have to use a monopole for this? There are much better approaches for electrically-short scenarios (all of which are basically clever ways of being less "short" in the same volume). For example, the Folded Unipole Antenna (FUA). If you only need narrow-band operation then you have lots of awesome options. What frequency (just curious)? \$\endgroup\$ Mar 29, 2013 at 5:51

1 Answer 1


A monopole antenna have a varying radiation resistance according to the ground plane size. You can use a series coil to eat up the capacitive parts of a short monopole and you would get a pretty good match with a 50ohm receiver front-end.


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