Microwave tomographic imaging of the breast for cancer detection is a topic of considerable interest because of the potential to exploit the apparent high-dielectric property contrast between normal and malignant tissue. An important component in the realization of an imaging system is the antenna array to be used for signal transmission/detection. The monopole antenna has proven to be useful in our implementation because it can be easily and accurately modeled and can be positioned in close proximity to the imaging target with high-element density when configured in an imaging array. Its frequency response is broadened considerably when radiating in the liquid medium that is used to couple the signals into the breast making it suitable for broadband spectral imaging. However, at higher frequencies, the beam patterns steer further away from the desired horizontal plane and can cause unwanted multipath contributions when located in close proximity to the liquid/air interface. In this paper, we have studied the behavior of these antennas and devised strategies for their effective use at higher frequencies, especially when positioned near the surface of the coupling fluid which is used. The results show that frequencies in excess of 2 GHz can be used when the antenna centers are located as close as 2 cm from the liquid surface.

中文翻译：

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有损液体介质中隐式电阻加载单极天线的表征。

用于癌症检测的乳房微波断层扫描成像是一个相当有趣的话题，因为它有可能利用正常组织和恶性组织之间明显的高介电特性对比。实现成像系统的一个重要组成部分是用于信号传输/检测的天线阵列。单极天线已被证明在我们的实施中很有用，因为它可以轻松准确地建模，并且可以在成像阵列中配置时靠近具有高元件密度的成像目标。当在用于将信号耦合到乳房的液体介质中辐射时，其频率响应显着加宽，使其适用于宽带光谱成像。然而，在更高的频率下，波束模式远离所需的水平面，并且在靠近液体/空气界面时可能会导致不需要的多路径贡献。在本文中，我们研究了这些天线的行为，并设计了在更高频率下有效使用它们的策略，特别是当它们位于所使用的耦合流体表面附近时。结果表明，当天线中心距离液面 2 cm 时，可以使用超过 2 GHz 的频率。特别是当靠近所用耦合液的表面时。结果表明，当天线中心距离液面 2 cm 时，可以使用超过 2 GHz 的频率。特别是当靠近所用耦合液的表面时。结果表明，当天线中心距离液面 2 cm 时，可以使用超过 2 GHz 的频率。