Research On The Microstrip Filter Antenna Array Fed By Series Adjacent Coupling

In RF front-end circuits,co-design of the filter and antenna can not only achieve good radiation,but also has the functions of impedance matching,filtering and balance conversion,which can effectively reduce the size of the system and the transmission loss.Filtering antennas are studied in this thesis.Two proximity-coupled antenna arrays with good filtering performances are designed.The main contents are as follows:Firstly,filtering mechanism of proximity-coupled feed is discussed.Equivalent circuit of antenna element is modeled,its impedance characteristics are analyzed.A 16-element linear uniform array is designed,which has broad bandwidth,good filtering characteristic and high frequency selectivity.Secondly,a series-parallel-fed 16×16 Ka-band high-gain low-sidelobe filtering antenna array is designed.Proximity-coupled 16-element Taylor linear arrays are taken as series subarrays,connected by parallel power divider networks with unequal amplitude and different phase outputs.Gain of 27.2dBi,sidelobe less than-15 dB are tested at 35 GHz.Proximitycoupled subarrays ensure the filtering characteristics of radiation pattern.Compared with parallel-fed array,feedline loss decreases 1.55 dB,and the design is more flexible.Thirdly,a proximity-aperture-coupled dual-band orthogonal-polarized filtering antenna is proposed.The designed frequency ratio is 1:1.1.Only one microstrip line is implemented to feed two patches with different frequencies and orthogonal polarization simultaneously.In the design,proximity-coupled feed ensures good frequency isolation;L resonators orthogonally reverse the polarization;U resonators introduced in aperture-coupled feed broaden the bandwidth.A series-fed 2-element array and a series-parallel-fed 2×4 array are composed.Measured results show broad bandwidths,good radiation characteristics,high frequency selectivity and frequency isolation.In this paper,the designed antenna arrays reveal high filtering performances without extra resonate circuits.They have good bandwidths and are convenient to form large arrays.Therefore,the proximity-coupled feed scheme has a unique advantage in realizing high gain,high efficiency antenna arrays and multifunctional shared-aperture microstrip antenna arrays.