Design And Research Of An Uwb Tem Horn Antenna And Array

High power microwave technology is widely used in radar,pulse radiation weapons and other fields.TEM horn antenna is the most common pulse radiation antenna because of its characteristics of ultra-wideband,high directivity,high power capacity and miniaturization.Because most of the energy of the unipolar pulse signal is concentrated in the low frequency part,it is particularly important to improve the efficiency of the pulse radiation system in the low frequency band.At the same time,because of the limited radiation ability of single antenna,array is often used to improve the radiation gain.In this paper,the low-frequency radiation characteristics of TEM horn antenna and array are studied,focusing on the impedance gradient,time-domain reflection,far-field radiation waveform,array grating lobes and other issues.1.The impedance gradient and time-domain radiation characteristics of the antenna are studied.The low radiation efficiency of the traditional antenna at low frequency is mainly due to the reflection of the radio waves gathered at the end aperture of the antenna at low frequency.Aiming at this problem,an end-loading structure is designed to solve the problem of reflection and low-frequency wave gathering at the end of the antenna,and improve the low-frequency radiation performance of the antenna.After adding the terminal loading structure,the antenna reduces the back lobe of the pattern in the whole frequency band,increases the spindle gain by about 2 dB at low frequency,and increases the low frequency bandwidth by about 400 MHz.Compared with similar antennas,the low-frequency radiation efficiency of the end-loaded antenna is higher,taking into account the low-frequency bandwidth and miniaturization.2.In order to solve the problem of insufficient gain of single antenna,the end-loaded antenna designed in this paper is used as the element to study the antenna array.The effects of element spacing,array arrangement and coupling on array gain are analyzed in frequency domain.According to the analysis results and the requirements of the index,a four-element antenna array is designed,with horizontal spacing 1100 mm,vertical spacing 900 mm and low frequency 3dB beam width 43.9 degrees.Compared with single antenna,the spindle direction gain of this quaternion array is increased by about 7.8 dB at low frequency.3.In order to feed array and solve the problem of insufficient power capacity of microstrip power divider network,a four-section seven-section coaxial power divider is designed,with relative bandwidth greater than 1.6.The power divider and antenna array are simulated jointly to obtain the far-field pulse waveform of the array.Compared with the loaded antenna at the end of the cell,the far-field radiation voltage of the antenna array is increased by about 3V while the low-frequency bandwidth of the array is guaranteed.