Research On Miniaturization Of Log-periodic Antennas

In the early 1950s,the logarithmic periodic antenna gradually entered people's field of vision,and was favored by antenna workers at home and abroad for a while.This article focuses on log-periodic antennas.Based on specific project requirements,two log-periodic antennas that can be used on different carrier platforms are designed.The main work of the paper is as follows:(1)Design of miniaturized folded logarithmic periodic antenna.This article designed a miniaturized folded logarithmic periodic antenna based on the project requirements.The operating frequency range was 2GHz?6GHz.The method of the vibrator reduces the lateral size of the antenna by 87%and achieves the purpose of miniaturization.According to the requirements of the project,the logarithmic periodic antenna is bent by90~0 along the collection line to achieve oblique polarization,while not affecting the electrical performance of the antenna.Next,the edge of the folded logarithmic periodic antenna is appropriately cut so that the antenna can be placed in a ship-shaped radome with a caliber of 136mm*103mm.Loaded radome integrated simulation optimization,Gain?2dB and voltage standing wave ratio VSWR?2.5 are achieved in the angles of-45~0?45~0,19~0?34~0 pitch(angle with the plane where the antenna is located),and the standing wave is well matched,and the gain basically meets the requirements.Reached the project indicators.(2)Design of miniaturized planar four-arm log-periodic antenna array.Based on the project requirements,this paper designs a miniaturized dual circularly polarized four-arm logarithmic periodic array antenna that works in thef _L?f_H frequency band and can be used for phased array.The array unit is loaded with a metal ring to make the unit size only ?=12mm(0.48?_H,?_H Refers to the wavelength corresponding to the high frequency).For the purpose of miniaturization,the gain of the antenna unit in the elevation range of-65~0?65~0and azimuth angle0~0?360~0 is Gain?-2dB.At the same time,the principle of sparse array is used.The dual circular polarization unit uses a concentric circular array.The arrangement of the rare cloth is optimized,and the array unit is optimized to finally form an 8+8+1 array.A total of 17 units are placed on the ?=150mm large floor,and the array gain reaches 19dB when not scanned,and the array gain reaches65~0 when it is scanned.10dB,the active standing wave at each port is below 2.5,and a wide-angle scan of±65~0 is achieved.It has good radiation characteristics and meets the requirements of the index.