Design Of Broadband Low-Profile Helix And Spiral Antenna And Underwater Missile-Borne Antenna

As an important device in wireless transmitting and receiving system,antenna is widely used in satellite navigation and missile communication systems.Considering satellite navigation measurement antennas as well as missile detection and telemetry antennas,the thesis focuses on the design of broadband and low-profile helix and spiral antenna,as well as the study of underwater missile-borne communication antenna.There are four different types of antenna designs involved in this thesis: a widebeam and compact quadrifilar helix antenna,a broadband and low-unroundness conical bifilar helix antenna,a low-profile and small-aperture Archimedean spiral antenna and an omnidirectional as well as conformal underwater missile-borne antenna for communication.The main work is as follows:First,the quadrifilar helix antenna(QHA)is used as a receiving antenna.The QHA is a resonating structure and left-hand circularly polarized,fed by two-stage Wilkinson power divider.The QHA is compact and well matched,and the axial ratio is better than 1.5d B within ±10° beamwidth,with the realized gain being larger than 4d Bic.Second,the conical bifilar helix antenna is designed for the purpose of antenna measurement,which covers all the operating frequency bands of the satellite navigation system.The VSWR is less than 1.5 and the AR is less than 1.5d B.Most importantly,the gain fluctuation of the antenna is less than 1d B within ±35° beamwidth to guarantee the measurement accuracy.Third,the low-profile Archimedean spiral antenna is designed for communication,in which case the antenna is mounted at the rear of the missiles to communicate with the ground station.Due to the limited space,the miniaturization of the antenna is very important,i.e.low-profile and small-aperture design is highly demanded.Then,Ferrite materials are adopted and tapered coaxial cable is used to feed the antenna,which could greatly reduce the height of the antenna.The height of the proposed antenna is only 0.015 wavelength in height at the lower frequency,and the axial ratio is less than 3.5d B.The front to back ratio is larger than 25 d B and the HPBW is about 60°.The isolation between two antennas is larger than 30 d B and the VSWR is less than 1.8.Finally,the missile-borne antenna is considered for underwater missile to ensure real-time communications with the ground station.Omnidirection is required due to the missile's dynamic characteristic.In addition,radome is utilized for waterproof,airproof,and conformability consideration.The geometrical parameters of the antenna are optimized under all constraints mentioned above and the VSWR is less than 1.8,with the realized gain of the antenna larger than-15 d Bi to guarantee the communication reliability.