By introducing a V-shaped air slot in antenna substrate, the peak gain can be improved significantly for traditional Vivaldi antennas without size enlargement and additional components. The air slot is conformal to the radiating conductors of the target Vivaldi antenna, and can force the electromagnetic wave to propagate within the central dielectric part between the antenna's opening slot, by decreasing the effective dielectric permittivity of the regions along the radiating conductors. As a result, the wave distributes more evenly within the radiating aperture comparing with the traditional designs, especially at high frequencies, hence the peak gain can be enhanced. In addition, the removal of antenna back substrate is evaluated on radiation characteristics, which can further improve antenna gain and front-to-back ratio. For verification, three antennas within operating frequency band from 0.8 to 6.0 GHz are designed with the same dimensions (220 mm × 256 mm) but different configurations. The simulations show that the peak gain increases from 2.0 to 12.0 dBi gradually for the air slot loaded antenna. The gain increment is about 4–6 dB from 4.0 to 6.0 GHz comparing with the one without air slot. A sample antenna with both air slot and removal of back substrate is fabricated and measured. The measured reflection is better than −10 dB from 0.8 to 6.0 GHz, and the measured gains at (0°,0°) direction are from 2.3 to 11.0 dBi. The antenna patterns at high-band shows that the main lobe in E-Plane is narrowed successfully after introducing the V-shaped air slot. The experimental data agree well with the prediction with in-band radiation efficiency better than 65%.

中文翻译：

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具有新颖 V 形气隙的高增益对映 Vivaldi 天线

通过在天线基板中引入 V 形气隙，可以显着提高传统 Vivaldi 天线的峰值增益，而无需增加尺寸和额外组件。气隙与目标维瓦尔第天线的辐射导体共形，通过降低沿辐射导体区域的有效介电常数，可以迫使电磁波在天线开口缝隙之间的中心介电部分内传播。因此，与传统设计相比，波在辐射孔径内分布更均匀，尤其是在高频时，因此可以提高峰值增益。此外，天线背板的去除对辐射特性进行了评估，可以进一步提高天线增益和前后比。为了验证，0.8 至 6.0 GHz 工作频段内的三根天线设计尺寸相同（220 mm × 256 mm），但配置不同。仿真表明，空气隙加载天线的峰值增益从 2.0 dBi 逐渐增加到 12.0 dBi。从 4.0 到 6.0 GHz，增益增量约为 4-6 dB，与没有空槽的相比。制造并测量了具有空气槽和去除背面基板的样品天线。在 0.8 至 6.0 GHz 范围内测得的反射优于 -10 dB，在 (0°,0°) 方向测得的增益为 2.3 至 11.0 dBi。高频段天线方向图表明，引入V形气隙后，E-Plane主瓣成功收窄。实验数据与预测相符，带内辐射效率优于65%。