Research And Design Of Ultra-Wideband Directional Antenna

Ultra-Wideband(UWB)technology plays an important role in UWB communication,satellite communication,anti-missile guidance,electronic countermeasures and ultra-wideband radar systems.In recent years,ultra-wideband systems have placed high demands on the bandwidth,miniaturization,and low-profile characteristics of ultra-wideband antennas.In this paper,several ultra-wideband directional antennas are designed from three application scenarios: base station communication,military electronic countermeasures,and groundpenetrating radar systems,respectively.The specific work is as follows:1.Design of an ultra-wideband dual-polarized antenna.A square-loop type ultra-wideband dual-polarization antenna is proposed to satisfy the requirements of ultra-wideband communications.The square-loop structure can improve the coupling between the loops while extending the current path,hence achieving good impedance matching,eventually the antenna port 1 can achieve a relative bandwidth of 88.7%(0.64～1.66GHz)and port 2 can achieve a relative bandwidth of 85.2%(0.66～1.64GHz)with port isolation greater than 22 d B,cross-polarization less than-22.4d B and the maximum gain is 9d Bi..Then a method to extend the bandwidth is proposed,by adding L-shaped metal walls around the ring structure,the loading of the metal walls introduces new resonant modes and extends the bandwidth,the relative bandwidth of this antenna port 1 is 109.2%(0.54～1.84GHz),the relative bandwidth of port 2 is 106.9%(0.5～1.65GHz),the isolation is greater than 22 d B,and Crosspolarization is less than-16 d B,the maximum gain in the band reaches 9.4d Bi with a minimum of 3d Bi and the directional pattern has good directionality.2.Design of a Conical Spiral Antenna.Planar directional spiral antennas are difficult to ensure the stability of the directional pattern over a wide frequency band due to the introduction of metal planes.A high-octave conical spiral antenna and a wide-angle spiral antenna are designed in the paper.The high-octave antenna has an impedance bandwidth of 174%(0.35～5GHz)and can maintain a stable directional pattern within 0.35～4.7GHz.The radiating arm of the wide-angle spiral antenna is wrapped around a 3D-printed dielectric column and achieves an impedance bandwidth of 75%(1.36～3 GHz)and an axial ratio bandwidth of 48.6%(1.4～2.3 GHz)through balun feeding,with the gain of the antenna is ≥0d Bi at ±48°and the axis ratio is ≤3d B at ±40°.3.Design of ground-penetrating radar antennas.The ground-penetrating radar antenna is usually designed with a butterfly antenna,but the butterfly antenna is difficult to feed and achieve broadband impedance matching.In this paper,a ground-penetrating radar antenna loaded with absorber material is designed to have an impedance bandwidth of 179%(0.12GHz～2.2GHz)and no "null depth" phenomenon.The antenna gain is up to 3.67 d Bi with YN-P-20 absorbing material and up to 0d Bi with YN-P-50 absorbing material.The ground-penetrating radar antenna is grouped in arrays of 11 transmitter and 11 receiver each.The measurement results show that the isolation between the transmitter is greater than 30 d B and between the transmitter and receiver is greater than 40 d B.The directional pattern and gain are less affected by the coupling of the units,and good radiation characteristics can be ensured.