Research On Key Technologies Of Antennas In High Speed Near-distance Communication

Close proximity communication technologies include RFID technology,NFC technology,and the emerging TransferJet technology.Among them,RFID near-field communication mostly lies in the UHF band,HF and LF bands,and NFC is in the 13.56 MHz HF band.They use the principle of electromagnetic induction to perform near field coupling.However,due to the lower frequency band,the transmission rate is slow and the antenna size is big.TransferJet technology combines the characteristics of ultrawideband(UWB)and Near-Field Communication(NFC)well.Its center frequency is at 4.48 GHz and has a transmission rate of up to 375 Mbps.However,it is still kept confidential due to the commercial policy of the TransferJet Consortium.It is difficult to use for secondary industrial development.A reasonable solution is to reform the existing 802.11 protocol so as to complete point-to-point high-rate information transmission in the situation of limited space,limited bandwidth.On the one hand,reduce power consumption and suppress spatial channel interference by reducing output power,on the other hand,antenna is an indispensable device in the communication system,it is of great significance to develop ultra-close proximity communication antennas which are suitable for the 802.11 protocol.In summary,based on the research background of high-speed ultra-close proximity communication antennas,this paper analyzes existing near-field technologies and adopts point-to-point communication to design four ultra-close proximity communication antennas that can be used under the technology mature 802.11 protocol.The main research is divided into two parts:1.A near-field antenna was designed based on a dipole structure.The antenna was composed of a folded double-loop dipole.The size of the antenna was reduced by bending the dipole,and by embedded the small dipole,we increased the Q factor and reduced the far-field radiation efficiency of the antenna,made it had less interference with adjacent communication devises and has good near-field coupling capability.After the antenna was simulated and processed,the near-field coupling effect of the antenna was tested from five directions and compared with the simulation result.The result showed that the antenna had good near-field coupling ability in the 2.4GHz WiFi frequency band.2.Three near-field antennas were designed based on the symmetrical microstrip resonator structure.The first microstrip open parallel resonant near-field antenna used parallel open-ended resonators,it reduced the far-field radiation and realized low gain effect by using the symmetrical current distribution and the back ground.The second antenna had a two-layer structure.The upper dielectric substrate was a ring coupler which consists of four parallel resonators,the radially distributed current of resonators produced a uniform near-field distribution,the lower dielectric substrate had a microstrip feed line and the ground,and copper pillars were used for feeding and grounding between the upper and lower substrates.The third near-field antenna changed the shape of the resonator,and the impedance matching was adjusted by using the microstrip tapered line on the edge of the resonator.The feed line was omitted and the resonant patch was close to the edge of the dielectric substrate,reducing the antenna size.The above three types of antennas have been simulated,fabricated and tested in five directions.The test results were consistent with the simulation.The results showed that the antennas had good near-field coupling capabilities in the frequency band.