Simultaneous transmit and receive (STAR) is attractive because it doubles spectral efficiency and alleviates radio frequency spectrum congestion. As expected, a major challenge in STAR is the high power leakage from the transmitter to the receiver, which dramatically reduces a receiver's dynamic range and then leads to desensitization. Therefore, it is paramount to ensure high transmit/receive (Tx/Rx) isolation. In this letter, we present a wideband STAR antenna array operating across 1.6–3.28 GHz (1 octave bandwidth), with a large transmit-to-receive isolation of 35 dB across the entire bandwidth. This is the first wideband and low, profile (λ/16 at the lowest frequency) STAR array retaining strong isolation when scanning down to 30° from broadside. The array elements are four-arm spirals, where two arms are for transmit and the other two for receive. To ensure high Tx/Rx isolation, symmetry is maintained everywhere in the structure, spiral arms, baluns, and feeds. The element spacing is kept at λ/2 at the highest frequency to avoid grating lobes. A 5 × 5 array prototype was built and tested to validate the design. Measurements show an excellent agreement with simulations.

中文翻译：

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用于同时发射和接收 (STAR) 的四臂螺旋元件的宽带扫描阵列

同时发送和接收 (STAR) 很有吸引力，因为它使频谱效率加倍并缓解了射频频谱拥塞。正如预期的那样，STAR 的一个主要挑战是从发射器到接收器的高功率泄漏，这会显着降低接收器的动态范围，然后导致灵敏度降低。因此，确保高发射/接收 (Tx/Rx) 隔离至关重要。在这封信中，我们展示了一个在 1.6–3.28 GHz（1 倍频程带宽）范围内运行的宽带 STAR 天线阵列，在整个带宽内具有 35 dB 的大发射到接收隔离度。这是第一个宽带和低剖面（最低频率下的 λ/16）STAR 阵列，当从舷侧向下扫描至 30° 时保持强隔离。阵元为四臂螺旋，其中两个臂用于发送，另外两个用于接收。为了确保高 Tx/Rx 隔离，在结构、螺旋臂、平衡不平衡变压器和馈电中的任何地方都保持对称。元件间距在最高频率处保持在 λ/2 以避免栅瓣。构建并测试了 5 × 5 阵列原型以验证设计。测量结果与模拟非常吻合。