By John Volakis, Chi-Chih Chen, Kyohei Fujimoto
Next-generation small antenna layout recommendations This authoritative textual content offers the main updated equipment at the conception and layout of small antennas, together with an in depth survey of small antenna literature released over the last a number of years. Written via specialists on the vanguard of antenna learn, Small Antennas: Miniaturization innovations & purposes starts off with a close presentation of small antenna theory--narrowband and wideband--and progresses to small antenna layout equipment, corresponding to fabrics and shaping techniques for multiband and wideband antennas. everyday miniaturization options are offered for narrowband, multiband, and wideband antennas. chapters dedicated to metamaterials antennas and techniques to accomplish optimum small antennas, in addition to a bankruptcy on RFID applied sciences and comparable antennas, are integrated during this finished quantity. assurance comprises: Small antenna conception and optimum parameters thought and boundaries of wideband electrically small antennas wide literature survey of small antenna designs useful antenna miniaturization techniques Conformal wideband antennas according to spirals unfavorable refractive index (NRI) metamaterial and electromagnetic band hole (EBG) dependent antennas Small antennas in response to magnetic photonic and degenerate band facet crystals Impedance matching for small antennas utilizing passive and lively circuits RFID antennas and know-how
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Extra info for Small Antennas: Miniaturization Techniques and Applications
Thiele (2003) observed that the exact lower limit for Q derived in earlier works was far from that of actual antennas and conjectured that the current distribution on the antenna had strong effect on the Chapter 1 : Survey of Small Antenna Theory value of Q .. His method for determining Q utilized an extension of the superdirective ratio concept. Thus1 his analysis was unique in deteqnining Q from the far-field pattern and not a modal expansion. Thiele applied his approach to a dipole antenna having non-uniform current distributionl and obtained favorable results as compared to practical dipole antennas with a similar current distribution.
It will later be shown [4, 5] that these patterns can be realized in the small antenna limit using certain arrangements of electric and magnetic monopoles. We close this discussion by nothing that Fig. 24 clearly shows the inverse relationship between antenna size·and antenna efficiency. Though this analysis was performed for one specific case, the principle generally holds for all small antennas. 4 Work of Collin, Rothschild, and Fante (1964-1969) Collin and Rothschild  sought to examine the antenna limits on by using a different method than Chu , based purely on the spherical TMrun and TErun fields generated by a Chu antenna.
Since the components cannot be easily separated, to evaluate Q Collin and Rothschild devised a method to separate the radiation component from the total stored electric and magnetic energy. The former can, of course, be found using Poynt ing's theorem. Without loss of generality, Collin and Rothschild choose to analyze only the TMnO mode of the Chu antenna. As discussed in Secs. 3, Q is independent of the azimuthal mode index m (the second 39 40 Small Antennas index of the mode). So, it was assumed zero for simplicity.