Investigations On The Compact High Gain Circularly Polarized Antenna

With the rapid developments and applications of the modern communication techniques, higher necessary of the communication systems is in great needed in miniaturization, integration and high performance these aspects. Compared with other components, antenna has some drawbacks such as the low level integration and performance. Therefore, the researchers have to design low-profile antennas with low-weight, robust and easy integration with planar devices. And also the antenna is the key element of the communication systems which can affect the whole system performance directly. So there is huge significance in designing these novel antennas which can be used in some special applications.Firstly, based on the traditional multi-modes substrate integrated cavity (SIC), modified substrate integrated cavity (MSIC) which can be applied in planar high gain circularly polarized antenna design has been proposed, then the relationship between the MSIC structure and the resonant frequencies of operating modes in MSIC is also given for the design convenience later.Next, chapter3 has reviewed the circularly polarized antenna measurement ways and the background of the cavity-backed antennas. Then, based on the MSIC, two gain enhancement ways which can be used in the planar high gain CP antennas have been proposed. Next, a planar high gain circularly polarized element antenna has been designed, fabricated and measured at C-band using the standard PCB process. The measured results have been matched with the EM simulation well which validate the correctness of our design.Finally, based on the two-dimensional GCPW structure, chapter4 have proposed, designed a compact array antenna feed network, and a 4*4 planar high gain CP array antenna have been implemented by integrating the feed network with the element antenna together. The measured results illustrate that the planar array antenna has achieved a radiation efficiency over than 80% and a larger gain than 20 dBi, and also presents that the planar high gain CP element antenna can be used in the planar array antenna design.