Research And Design Of GPS Antenna And Its Dual Frequency Technology

With the continuous development of Global Positioning System (GPS), terminal antenna of the system is facing more challenges. So research on the antenna has become a hotspot of scientific research. GPS includes the frequency bands of GPS L1 and L2. And microstrip circularly polarized antenna is the common way of this antenna. This thesis is aimed at studying and designing the single band and dual-band microstrip circularly polarized antenna of GPS bands. The main work can be separated as the following segments.1. This thesis introduces the development situation of circular polarization antennas at home and abroad. Then the realization techniques of circular polarized helix antennas and microstrip antennas, multiband of circular polarization antenna are introduced. The related theory of microstrip antenna, the common theoretical methods of antenna analysis and implementation methods of circular polarization are expounded.2. A GPS antenna based on the DGS (Defected grounded structure) structure is designed. The antenna is applied in the GPS L1 frequency band using the coaxial cable to feed the antenna. The mechanism of the circularly polarized antenna is to excite two orthogonal modes in the diagonal direction with the same amplitude and phase difference of 90 degrees. The way of doing this is to open the rectangular slots and circular slots along the diagonal directions respectively, thus forming the circularly polarized wave. To enhance the bandwidth and gain of the antenna, E-shaped DGS structures are utilized. The results show that the minus 10dB impedance bandwidth and gain are strengthened after etching E-shaped DGS on the ground plane. The bandwidth has increased 0.61% and the gain has been enhanced 0.61dB. Finally, the antenna is fabricated and measured. Measured results have slight deviation from simulated results, and this thesis has analyzed the deviation.3. A dual-band circularly polarized stacked antenna is designed. The antenna is working at the GPS L1 and L2 frequency bands. The antenna is fed by coaxial probe. The upper patch is directly fed by the coaxial probe. The lower layer is fed through the coupling between the upper and the lower layers. The two patches can realize circular polarization separately. They are combined together to form the dual-band circularly polarized antenna with stacked structure. The-10dB impedance bandwidths are 3.7% and 5.2% and the simulated and 3dB circular polarization bandwidths are 0.855% and 0.73% respectively. The antenna is fabricated and measured. Measured results have deviation compared with the simulated results, and this thesis has analyzed causes of the deviation. Through many times of improvement, the antenna can satisfy the basis requirements and the general experience in simulation and tuning is given in this thesis.