K-band Slot-loop Antenna

With the rapid increase of the number of vehicles,the demand of the huge parking pressure on the parking lot and parking space is also higher and higher.With the rapid development of Internet of Things(IOT)technology and intelligent parking system,automatic parking equipment has been applied to the parking system.Taking into account the accuracy,price and service life of the automatic parking equipment,the Kband(18?27GHz)antenna that meets the requirements of high gain,small size and high front-to-back ratio can be used in the parking system to receive and transmit electromagnetic waves.The antenna is used to receive and transmit electromagnetic waves.On this basis,the research and design of K-band annular slot array antenna for parking system are carried out.On the basis of a lot of research,this paper has done the following work:(1)In this paper,the principle of slot-loop antenna is described,and a novel slotloop antenna based on traditional slot-loop antenna and fed by coplanar waveguide is designed.There is a circle of through holes around the current path of the antenna to reduce the loss caused by the diffusion of electromagnetic wave in the substrate.The antenna achieves S11 less than-10 d B in the working bandwidth(22.7 ? 26.8 GHz),and the simulated gain of the antenna is 7.61 ? 8.15 d Bi.The antenna has good directional radiation characteristics in the upper working band.(2)Based on the slot-loop first antenna,a series fed slot-loop array antenna is designed and manufactured.The bottom surface of each ring slot antenna is cut in the center,and the coplanar waveguide is used to transmit energy to the antenna,which is connected to the top of the antenna through a microstrip line.The microstrip line in the lower ring slot element continues to feed the upper ring slot element,so as to realize series feed.The antenna achieves S11 less than-10 d B in the working bandwidth(23.3? 25.9 GHz),has good impedance matching characteristics,and has a maximum gain of 10.75 dbi,which ensures the high test accuracy of the test system.The size of the antenna is 16 mm × 28 mm × 1.524 mm,with a small size of 0.12 ?(? is the free space wavelength corresponding to 24GHz).(3)Based on the series fed slot-loop array antenna,a slot-loop antenna with choke is designed.The antenna uses a choke ring with a spacing and height of about a quarter of the wavelength.Two implementations are designed,and the antenna is tested.The first is a choke that is highly consistent with the antenna itself.The S11 less than-10 d B band is 23.0?25.5GHz when the antenna is actually tested,and the test gains are all greater than 9.51 d Bi.The front-to-back(F/B)ratio of the actual test is above 20 d B.The second is a choke ring 2 mm above the antenna height.Place electroplated holes on the FR4 dielectric plate,screw the two dielectric plates together with nylon studs and weld the holes.S11 is less than-10 d B within the working bandwidth(23GHz ?25.7GHz),has an actual test gain greater than 9.18 d Bi across the bandwidth,and has a radiation pattern with F/B ratio more than 25 d B and a maximum gain of 11.99 d Bi at24 GHz.The overall size of the antenna is 48.52 mm × 60.75 mm × 3.524 mm,and it has a small low profile size of 0.28lambda(the corresponding free space wavelength of lambda at 24GHz).