Investigations On The Fusion Design Of Filtering Antennas

In wireless communication systems,the RF devices are driven to be miniaturized,integrated and low loss.Antennas and filters are two important components in RF front end.In traditional approach,they are individually designed and cascaded together.The matching circuit between them would occupy more footprint size,bringing about extra loss.Recently,filtering antennas have become a topic of concern in antenna field.The integration of filter and antenna based on fusion design approach simultaneously possesses radiation and filtering function,leading to miniaturized size and enhanced overall performance of RF front end.In this paper,the fusion design of filtering antennas is investigated.Three techniques of realizing filtering antennas have been proposed based on the fusion design theory.According to the techniques,a series of filtering antenna elements have been realized.The main work of this paper is as follows:1.A technique of realizing filtering antennas by using simple parasitic elements is proposed.Based on the technique,?1?A low profile wideband and high gain filtering antenna based on metasurface?MS?is realized.The antenna has a bandwidth of 28.4%,an average gain of 8.2dBi,and an out-of-band suppression level of more than 20dB.?2?A broadband filtering dielectric resonator antenna?DRA?with harmonic suppression is realized.The antenna possesses a 10-dB bandwidth of 61%,an average gain of 8.73 dBi within passband and a suppression level of more than 23 dB within wide stopband.2.A technique of realizing filtering antennas by using the transmission zeros of microstrip feed-line is proposed.Based on the technique,?1?A wideband and high gain filtering DRA is realized.The antenna has a 10-dB impedance bandwidth of 20.3%,an average gain of 9.05dBi and an out-of-band suppression level of more than 25dB.?2?A quasi-isotropic filtering DRA is first realized.The antenna with a radius of 0.13?has an enhanced bandwidth of 7%,quasi-isotropic radiation field with the difference between the maximum and minimum power density given by 7.9dB,and out-of-band suppression level of more than 19dB.3.A technique of realizing filtering antennas by using hybrid feed is proposed.Based on the technique,?1?Wideband/dualband omnidirectional filtering DRAs are realized.The wideband design has a bandwidth of 52.8%,an average gain of 0.84dBi and an out-of-band suppression level of¹5dB.The dualband design has a bandwidth of 10.1%and 3.73%and an average gain of 1.1dBi and 0dBi,as well as an out-of-band suppression level of¹5dB.?2?Single/dual polarized filtering DRA is realized.The antenna has 10-dB impedance bandwidth of 22.5%,an average gain of 5dBi with efficiency up to 89%within passband,an out-of-band suppression level of more than 16dB with high frequency selectivity(rectangular coefficient K=?35?f_-35dB/?35?f_-3dB=1.4),and an isolation of more than 21dB between the two ports.?3?A filtering patch antenna with reconfigurable frequency and bandwidth is realized.The antenna possesses continuously tunable operating frequency?2.05-2.52GHz?and bandwidth?2.2%-21.3%?with good bandpass response.The gain is between 6.4-7.6dBi in different states.Also,the antenna shows second harmonic suppression.