Research On Complementary Source Antenna And Array Based On Transmission Line Mode Design

As a special type of radiation source that integrates electric current radiation source and magnetic current radiation source,complementary radiation sources have the potential to construct antenna radiation characteristics in a compact space.The traditional comple-mentary source antenna has the advantages of broadband and stable gain,but the structure is relatively complex,and the form is relatively solid.In this dissertation,the perspec-tive of transforming single-mode and multi-mode transmission lines is used to introduce the complementary source radiation mechanism,and the microstrip transmission line is used as the representative of the open transmission line to analyze how to transform the open transmission line to realize the complementary source radiation.Several microstrip-based complementary source antennas with a half-power beamwidth of 180?are proposed.At the same time,the complementary source radiation mechanism based on the transmis-sion line is extended to the closed transmission line represented by the substrate integrated waveguide(SIW),which verifies its potential in wide-beam radiation and backward radia-tion suppression.In this dissertation,the single-mode transmission line is further extended to the multi-mode composite transmission line,two compact multi-mode composite trans-mission lines are discussed,and their application potential in multi-mode complementary source antennas is verified.this dissertation takes the single-mode and multi-mode design of transmission lines as perspective and transforms the transmission lines to realize complementary source ra-diation to design high-performance microwave and millimeter-wave antennas.The main research can be divided into the following three aspects:1.Research on microstrip monopole composite complementary source antenna based on single-mode open transmission line.Taking the microstrip line as an example of an open transmission line,how to destroy the symmetry of the transmission line field dis-tribution by parasitic monopoles structure is studied to achieve effective radiation.The microstrip line will be equivalent to magnetic current radiation sources,and the parasitic monopole radiation structure will behave as electric current radiation sources,forming an orthogonal complementary radiation source.Based on the special unidirectional radiation feature of complementary radiation sources,this dissertation starts from the unit and grad-ually transitions to array design,and three antennas are used to fully explain the special advantages of loaded parasitic electric current radiation sources in broadening the antenna bandwidth and designing wide-beam radiation.One is to use a half-wavelength wide microstrip line as the basis and load a parasitic monopole structure on one side to form a special end-fire antenna.The antenna is compact and simple in structure and has excellent bandwidth?the second is to parasitize a monopole antenna on each side of the traditional microstrip antenna to form two pairs of complementary radiation sources,in which the equivalent magnetic current source is out of phase,and the current radiation source is in the same phase.As a result,the two pairs of complementary sources have symmetrical inclined beams,thereby realizing wide-beam radiation,and the antenna achieves an ex-cellent 180?1-d B wide-lobe performance?the third is alternately and periodically loading parasitic monopoles at the two sides of microstrip line to realize the cascaded complemen-tary sources array.Array mechanism can effectively improve the antenna gain,and also achieves more than 180?half-power beamwidth.2.Research on complementary source array antenna based on single-mode closed transmission lines.On the one hand,the mechanism to achieve wide-beam radiation is continued to use,and the wide-beam complementary source radiation scheme is extended to the closed transmission line represented by SIW,which achieves a smoother and more symmetrical radiation pattern.And through the transformation of the electric current ra-diation source,the wide-beam complementary source array antenna is flattened.The two wide-beam complementary source antennas based on the SIW transmission line design both have a half-power beamwidth of 180?.Compared with the wide-beam array case based on the microstrip line,the closed-type transmission line-based scheme achieve a smoother radiation pattern,and the radiation performance is easier to adjust.The planar design can also effectively improve the integrability of the antenna.On the other hand,for the planar complementary source array antenna,a single-layer planar complementary source array antenna is proposed based on the half-mode substrate integrated waveguide(HMSIW)transmission line.For the traditional cavity cascaded array antenna with the same size,the introduction of complementary source radiation improves the front-to-back ratio of the antenna by more than 20 d B.3.Research on complementary source antenna based on multi-mode composite trans-mission lines.The substrate-integrated multi-mode composite transmission line is studied and analyzed,and its application in millimeter-wave multi-mode antenna is discussed with its excitation on complementary sources of radiation.A millimeter-wave dual-polarized end-fire complementary source array antenna is designed based on the transmission line of TEM mode and TE₁₀mode.Through the dual-mode composite feed network,the complex problem of the dual-polarized millimeter-wave array antenna feed network is effectively simplified,and the efficient mode isolation also enables the designed millimeter-wave dual-polarized array to have good port isolation and cross-polarization isolation.The 8-element linear array achieves an impedance bandwidth of 26.9%,covering the frequency band from 24.3 GHz to 32.5 GHz.The test results show that the port isolation between the horizontal polarization mode and the vertical polarization mode exceeds 36 d B,and the cross-polarization of the two modes is also less than-30 d B.Based on the dual-mode trans-mission line,a three-mode integrated substrate-integrated composite waveguide is further proposed,which supports TEM mode,TE₁₀mode,and a special folded TE₂₀modes are supported simultaneously,and the fields of the three modes share the same waveguide structure.A polarization/pattern diversity antenna is conceived based on a three-mode composite transmission line,in which the TEM mode is used to excite a hollow beam of radiation,the TE₁₀mode is used to excite vertically polarized radiation,and a special folded TE₂₀mode can excite horizontally polarized radiation.