Broadband Base Station Antennas With Electromagnetic Transparency

Broadband antennas with electromagnetic transparency are proposed in the thesis.As for a normal antenna,the scattering effect can be suppressed by loading slots on the dipoles.If the induced currents of higher frequencies are distributed on the designed dipoles,they will be led to flow in the opposite directions and reduced at the same time,so that the scattered waves can be eliminated each other and have not much left in the end.How to load the U-shaped slots on the dipoles is important in the design.The distributions of high-frequency induced current and low-frequency exciting current are both changed by the loading of U-shaped slots.Besides the two resonance points from the crossed dipoles,in the operating band,the reflection coefficient curve has an extra resonance point,which is related to the loading of U-shaped slots.Thus,the impedance matching of electromagnetic transparent antenna can be improved.LB,HB and CB are used to represent the frequency bands of 0.69-0.96,1.71-2.69 and 3.3-3.8 GHz(partially or completely),respectively.The main contents of the thesis are as follows:1.A wideband HB antenna with electromagnetic transparency in the band of 3.4-3.8 GHz is proposed.Operating in the band of 1.71-2.69 GHz,it can suppress CB scattered wave with slots on the HB patch dipoles.In the operating band,each reflection coefficient curve has three resonance points,thus achieving a good impedance matching(VSWR<1.5).2.A wideband LB antenna with electromagnetic transparency in the band of 1.7-2.4 GHz is proposed.Operating in the band of 0.69-0.96 GHz,it can suppress HB scattered wave with slots on the LB patch dipoles.In the operating band,each reflection coefficient curve has three resonance points,thus achieving a good impedance matching(VSWR<1.5).3.A wideband LB antenna with electromagnetic transparency in the band of 3.3-3.8 GHz is proposed.It operates in the band of 0.69-0.96 GHz.The component unit of the dipole arm is a slot-loaded metal strip.To suppress CB scattering,some units are connected and arranged in the mesh structure.In the operating band,each reflection coefficient curve has three resonance points,thus achieving a good impedance matching(VSWR<1.3).4.A wideband LB antenna with electromagnetic transparency in the bands of 1.7-2.2 and3.3-3.8 GHz is proposed.It operates in the band of 0.69-0.96 GHz.The LB dipole arm can be formed by the connection of some slot-loaded metal strips,with a special topological structure to suppress both HB and CB scattering.In the operating band,each reflection coefficient curve has three resonance points,thus achieving a good impedance matching(VSWR<1.5).