This article presents a compact absorptive filtering patch antenna. It consists of a filtering patch antenna and a bandstop filter (BSF), with their transfer functions being complementary to each other. A slot is fabricated in each of the patch and ground, giving a total of two radiation nulls for the lower bandedge. By using a dual-stub feed, two radiation nulls are also obtained for the upper bandedge. For the BSF, a $\lambda _{\mathrm {g}}$ /2 defected ground structure (DGS) and a $\lambda _{\mathrm {g}}$ /4 defected microstrip structure (DMS) are used in the design. It is terminated by a chip resistor. Since the filtering patch antenna and BSF have complementary transfer functions, the incident energy can be radiated effectively in the passband but largely absorbed by the resistor in the stopbands. As a result, only little energy will be reflected over a wide frequency range, giving a reflectionless characteristic. To demonstrate this idea, an absorptive filtering antenna operating at 5.8 GHz was designed, fabricated, and tested. Its impedance is matched from 5 to 6.5 GHz, with the measured out-of-band suppression being higher than 17 and 20 dB for the lower and upper stopbands, respectively. The measured peak realized gain is 7.28 dBi.

中文翻译：

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紧凑型吸收滤波贴片天线

本文介绍了一种紧凑型吸收滤波贴片天线。它由滤波贴片天线和带阻滤波器 (BSF) 组成，它们的传递函数互为补充。在每个贴片和地中制造一个槽，为较低的带边提供总共两个辐射零点。通过使用双短线馈电，还可以为上带缘获得两个辐射零点。对于 BSF，一个 $\lambda _{\mathrm {g}}$ /2 缺陷接地结构 (DGS) 和 $\lambda _{\mathrm {g}}$ /4 缺陷微带结构 (DMS) 用于设计。它由一个片式电阻器终止。由于滤波贴片天线和 BSF 具有互补的传递函数，入射能量可以在通带中有效辐射，但在阻带中大部分被电阻吸收。因此，在很宽的频率范围内只会反射很少的能量，从而具有无反射特性。为了证明这个想法，设计、制造和测试了一个工作在 5.8 GHz 的吸收滤波天线。其阻抗匹配范围为 5 至 6.5 GHz，测得的带外抑制分别高于低阻带和高阻带的 17 dB 和 20 dB。测得的峰值实现增益为 7.28 dBi。