Dual-Polarized Filtering Magneto-Electric Dipole Antenna Utilizing Intrinsic Highpass Filter Network and Integrated Lowpass Filter Network

This paper presents an effective design method to integrate bandpass filtering response into an aperture-fed dual-polarized magneto-electric dipole antenna (ME-dipole). The antenna is composed of a traditional ME-dipole radiator and a modified aperture-coupled feeding structure. In one aspect, highpass filtering radiation response is realized by approximating the antenna radiator as a highpass filter network. In another aspect, by developing an improved aperture-coupled feeding structure with lowpass filter characteristic, the antenna obtains lowpass filtering radiation response. As a result, bandpass filtering radiation response is achieved. Since no intricate filter resonators are used, the in-band antenna gains are not degraded. The highpass/ lowpass filter networks are studied and specific radiation nulls generated by the two networks are analyzed. For demonstration, a single-polarized model is presented first and its working mechanism is studied in detail. It realizes a 78.6% impedance bandwidth, flat in-band gains of 7.5 -7.8 dBi, and more than 22 dB out-of-band radiation suppression level. Then, based on the same methodology, a dual-polarized antenna model is developed with 69.3 % operating bandwidth, 7.1 -9.3 dBi measured in-band gains and integrated bandpass filtering radiation response.