Multi-mode Resonance Theory And Its Applications In Handheld Terminal Antenna Designs

This thesis is devoted to the research of multi-mode resonance theory of antennas.Firstly,theoretical criterion of the prototype dipole's length is laid down based on the simplest dipole model and the associated eigenmodes.Then a generalized design approach to compact wideband multi-mode resonant patch antenna is proposed and a series of novel broadband patch antennas with different performances are designed and investigated.At the same time,it is verified that the theory can still play a prominent role in complex irregular structures and harsh environments.The main content of this thesis includes:1.The multi-mode resonance condition of the dipole antenna?prototype vibrator antenna?is strictly proved by the wave equation:its length must be the integer multiple of the one-half wavelength,which reveals that the cosine-and sine-dependency are alternating for odd-and even-order dipole current distributions.2.The pattern mapping relationship between prototype dipole antenna and microstrip patch antenna is established,which reveals the general law between prototype dipole antenna,resonant mode,size and radiation characteristics.The condition of microstrip patch antenna under multi-mode resonance is derived,and the multi-mode design method for circular sector patch antenna is presented in tabular form.A compact dual-mode patch antenna is designed and implemented by choosing TM_4/3,1 and TM_8/3,1 modes of microstrip patch element with a flared angle of 240°.3.The proposed multi-mode resonance theory can be extended to general situations such as irregular structures and harsh environments.By fully exciting the multi-band characteristics of the loop-dipole antenna,it can cover most mobile communication bands such as GSM850/900,DCS1800,PCS1900,UMTS2100,TS-SCDMA,etc.A dipole-loop antenna suitable for all-metal packaging has been designed successfully,which well proves the generality of the multi-mode resonance theory.