In this paper, we introduce a novel and compact double-ridged horn (DRH) antenna for ultra-wide band microwave imaging. We first develop theoretical considerations useful to derive effective design guidelines and, thus, realizing the antenna model. Afterwards, an electromagnetic numerical solver is employed to study the conceived antenna both in free space and in the presence of a biological load; in both the simulation set-ups, excellent radiating performance are obtained, demonstrating the antenna robustness. Finally, a prototype is fabricated and experimentally measured to validate the final design. The proposed model presents overall dimensions that are 30% smaller with respect to traditional and commercially available DRH antennas (151 mm $\times108$ mm $\times146.6$ mm), retaining, at the same time, a significantly large operative band (VSWR < 3 over the 1–9 GHz band). Among the broad class of possible applications, this frequency range is particularly suitable for biomedical devices, such as in microwave imaging, where reduced dimensions are fundamental in order to allow an easy integration within these systems. In addition, a safety assessment has been performed on the designed antenna, demonstrating that SAR is well below the regulating limits and it can be safely used in proximity of human operators.

中文翻译：

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用于超宽带微波成像的紧凑型双脊喇叭天线

在本文中，我们介绍了一种用于超宽带微波成像的新型紧凑型双脊喇叭 (DRH) 天线。我们首先制定了有助于推导出有效设计指南的理论考虑，从而实现天线模型。然后，使用电磁数值求解器在自由空间和存在生物负载的情况下研究设想的天线；在这两种仿真设置中，都获得了出色的辐射性能，证明了天线的稳健性。最后，制造原型并进行实验测量以验证最终设计。与传统和商用 DRH 天线（151 mm $\times108$ 毫米 $\times146.6$ mm)，同时保留了一个非常大的工作频段（VSWR < 3 在 1-9 GHz 频段上）。在众多可能的应用中，该频率范围特别适用于生物医学设备，例如微波成像，在这些设备中，减小尺寸是基础，以便轻松集成到这些系统中。此外，还对设计的天线进行了安全评估，证明 SAR 远低于监管限制，并且可以在人类操作员附近安全使用。