This paper presents a fluidically loaded microstrip patch antenna on a multi-layered substrate with frequency and polarization reconfigurability in the 2400 MHz band. A square patch loaded at all the corners with short circuited $\lambda _{g}/4$ long stubs is utilized. An arrangement of fluidic channels fabricated by moulding Polydimethylsiloxane (PDMS) with 3D printed mould is incorporated beneath each stub. By injecting or withdrawing distilled water into the channels, variable loads are realized. It exhibits frequency tunable linearly polarized (LP) mode with symmetric loading or circularly polarized (CP) mode with asymmetric loading. The sense of CP can be switched by swapping the loading configuration along the diagonals of the patch. The equivalent circuit for the antenna is presented. A prototype is fabricated and measured. In LP mode, frequency tuning of 7.85% is achieved. The minimum realized gain is 5.67 dBi with cross-polarization (X-pol) isolation $\geq20$ dB. In the CP modes, the overlapping bandwidth for ${\mid }\text{S}_{11}{\mid } \leq -10$ dB and axial ratio $\leq3$ dB (ARBW) is $\geq16$ MHz for both LHCP/RHCP modes. Frequency tuning of 141 MHz (5.76%) is measured in the RHCP mode. The minimum realized gain is 4.86 dBic and total efficiency is >60%.

中文翻译：

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短截线加载的贴片天线，用于频率可调的极化重新配置

本文提出了一种在多层基板上流体加载的微带贴片天线，该天线在2400 MHz频段具有频率和极化可重构性。方形贴片在所有角落都装有短路 $ \ lambda _ {g} / 4 $ 使用长存根。通过每个3d打印模具模制聚二甲基硅氧烷（PDMS）制成的流体通道的布置都包含在每个桩下面。通过将蒸馏水注入或抽取到通道中，可实现可变负载。它具有对称负载的频率可调线性极化（LP）模式或不对称负载的圆极化（CP）模式。可以通过沿着贴片对角线交换加载配置来切换CP感。给出了天线的等效电路。原型被制造和测量。在LP模式下，可实现7.85％的频率调谐。具有交叉极化（X-pol）隔离的最小实现增益为5.67 dBi $ \ geq20 $ D b。在CP模式下， $ {\ mid} \ text {S} _ {11} {\ mid} \ leq -10 $ dB和轴比 $ \ leq3 $ dB（ARBW）是 $ \ geq16 $ LHCP / RHCP两种模式下的MHz。在RHCP模式下测得141 MHz（5.76％）的频率调谐。最小实现增益为4.86 dBic，总效率> 60％。