A filtering dielectric resonator (DR) antenna (DRA) that does not require any filtering circuits is investigated. It deploys a rectangular DR and three slots fabricated in the ground plane. The antenna is excited in the fundamental TE $^{y}_{1\delta 1}$ DRA mode and two slot modes. By making use of these three modes, two tunable radiation nulls near the edges of the passband can be obtained, giving filtering effects without the need for any filtering circuits. In this article, the design, with minor modifications of the slots, is extended to a frequency-reconfigurable filtering DRA by using varactors. Its stopband can be extended to the third harmonic. By varying the voltages of the varactors, the antenna has continuous frequency agility of 27.7% (2.15–2.84 GHz), with almost the same harmonics suppression level. The antenna has a gain of ~5.0 dBi and a rejection level of over 16.1 dB across the stopband. Its total antenna efficiency in the passband is ~81%, whereas it is generally lower than the average value of 1.8% in the stopband (up to 7.0 GHz). Compared with the reported frequency-reconfigurable filtering antennas, our design has better frequency agility, more stable filtering response, and weaker radiation in the stopband.

中文翻译：

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具有谐波抑制功能的频率可重构滤波介质谐振天线

研究了一种不需要任何滤波电路的滤波介质谐振器 (DR) 天线 (DRA)。它在接地平面中部署了一个矩形 DR 和三个插槽。天线在基本 TE 中被激发 $^{y}_{1\delta 1}$ DRA 模式和两种插槽模式。利用这三种模式，可以获得通带边缘附近的两个可调辐射零点，无需任何滤波电路即可提供滤波效果。在本文中，该设计对插槽进行了少量修改，并通过使用变容二极管将其扩展为频率可重构滤波 DRA。它的阻带可以扩展到三次谐波。通过改变变容二极管的电压，天线具有 27.7% (2.15–2.84 GHz) 的连续频率捷变，具有几乎相同的谐波抑制水平。该天线的增益为 ~5.0 dBi，阻带范围内的抑制水平超过 16.1 dB。它在通带中的总天线效率约为 81%，而它通常低于阻带（高达 7.0 GHz）中 1.8% 的平均值。