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In general terms, at any given frequency the log-periodic design operates somewhat similar to a three-element Yagi antenna; the dipole element closest to resonant at the operating frequency acts as a driven element, with the two adjacent elements on either side as director and reflector to increase the gain, the shorter element in front acting as a director and the longer element behind as a reflector. However, the system is somewhat more complex than that, and all the elements contribute to some degree, so the gain for any given frequency is higher than a Yagi of the same dimensions as any one section of the log-periodic. However, it should also be noted that a Yagi with the same number of elements as a log-periodic would have ''far'' higher gain, as all of those elements are improving the gain of a single driven element. In its use as a television antenna, it was common to combine a log-periodic design for VHF with a Yagi for UHF, with both halves being roughly equal in size. This resulted in much higher gain for UHF, typically on the order of 10 to 14 dB on the Yagi side and 6.5 dB for the log-periodic.<ref>{{cite book |url=https://books.google.ca/books?id=jDCs1Ckne_EC&pg=PA177 |page=178 |title= Computational Electromagnetics for RF and Microwave Engineering |first=David |last=Davidson |publisher=Cambridge University Press |date=2010}}</ref> But this extra gain was needed anyway in order to make up for a number of problems with [[UHF television broadcasting#UHF vs VHF|UHF signals]].
It should be strictly noted that the log-periodic shape, according to the IEEE definition,<ref>“''Log-periodic antenna'' Any one of a class of antennas having a structural geometry such that its impedance and radiation characteristics repeat periodically as the logarithm of frequency.” (see ''The new IEEE Standard Dictionary of Electrical and Electronics Terms'', 1993 ⓒ IEEE.) </ref><ref>“''Log-periodic antenna'' Any one of a class of antennas having a structural geometry such that its impedance and radiation characteristics repeat periodically as the logarithm of frequency.” (see Acknowledgments, and footnote in page 1), ''Self-Complementary Antennas―Principle of Self-Complementarity for Constant Impedance''―, by Y. Mushiake, Springer-Verlag London Ltd., London, 1996</ref> does not
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