Research On C-band Cylindrical Circularly Polarized Conformal Antennas

With the wide application of the circularly polarization in more and more fields,the carriers of its elements are becoming more and more diverse.The antenna is required to work normally without destroying the volume and physical appearance of the carrier due to the compact space on the communication equipment.The exposed antenna on a high speed moving carrier is also required to be non-destructive to the carrier's aerodynamic performance.Based on these problems,the circular polarized cylindrical conformal antenna is studied.(1)A simple implementation method of the low profile circularly polarized microstrip antennaBased on the wide application of low profile circularly polarized antennas,a simple implementation method of the low profile perturbation-based circularly polarized antenna is proposed.By introducing the perturbation hole on the grounded planar,the structure of the radiation patch is not damaged,which reduces the frequency shift due to the perturbation element.Because of the position of the perturbation hole is fixed on a straight line,the design procedure of the traditional circularly polarized microstrip antenna is simplified.After research,the antenna has the advantages of low profile,high gain and simple design,which can be applied to WLAN(5.8GHz)wireless communication system.(2)Broadband circularly polarized conformal antenna based on coplanar waveguide-fedA broadband circularly polarized conformal microstrip antenna based on coplanar waveguide-fed is proposed to meet the development needs of broadband antennas in conformal applications.By introducing a pair of disturbing branches on the rectangular grounded metal frame and protruding a pentagonal monopole,the measured 3-d B axial ratio bandwidth and-10-d B impedance bandwidth are 58.5%(4.6?8.4 GHz)and 67.7%(4.3?8.7GHz),respectively.The antenna has the advantages of small shape,low profile and low manufacturing cost.Simulated and measured results indicate that the antenna has good adaptability to cylindrical carriers with different radius,which is suitable for potential conformal applications.In addition,the antenna can be applied to WLAN(5,5.2 and 5.8 GHz),Wi MAX(5.5GHz)and other C-band wireless communication systems.(3)Double-layer circularly polarized conformal antenna based on the V-shaped branch coupled-fed structureAgainst the background of the wide demand of circularly polarized conformal antennas working on metal carriers,a double-layer grounded planar circularly polarized conformal antenna with V-shaped branches coupled feeding structure is proposed.Two resonant modes are generated by cutting one vertex of the octagonal patch to broaden the operational bandwidth.An L-shaped ground plane is designed on the back of the top substrate.This configuration can obtain a relative compact phase shifter on the one hand and makes the coupling branches and octagonal patch share one ground plane on the bottom,improving the thickness of the antenna which yields wide bandwidth on the other hand.The proposed antenna can own good performances both in the planar and cylindrical carriers.Under the cylindrical conformal circumstance,the measured|S₁₁|and axial ratio(AR)bandwidth reaches 12.05%(5.5GHz-6.205GHz)and 8.93%(5.67GHz-6.2GHz),respectively.The measured peak gain is8.5d Bic.The proposed antenna has the advantages of wide bandwidth,high gain,low cost,and easy installation,which can be applied to wireless communication systems working in WLAN(5.8 GHz)and part of the C-band.