Ka-band wideband harmonic-suppression directional coupler
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摘要: 为解决传统分支线定向耦合器带宽较窄,且应用到线性化器等微波元件中时受谐波信号影响较大的问题,提出了一个宽带且带有谐波抑制功能的定向耦合器。该定向耦合器在双支节定向耦合器的基础上增加一个支节,可有效地提高定向耦合器的带宽,同时将其传输线支节替换为低通滤波结构,以实现对高次谐波抑制的作用。仿真结果表明,该定向耦合器的反射系数和隔离度均小于-15 dB,传输损耗小于3.8 dB,波动范围0.5 dB,相位差为90°且与双支节耦合器相比增加1 GHz带宽。满足耦合器的设计指标,可应用到微波元件中,提高微波元件的性能。Abstract: In order to solve the problem that the traditional directional coupler has a narrow bandwidth and is greatly influenced by harmonic signals, this paper presents a broadband directional coupler with the function of harmonic suppression. The directional coupler adds a branch section to double-branch-line directional coupler, thus can effectively improve the bandwidth. While its transmission lines are added with low-pass filter structures, it can filter harmonics well. The experimental results show that the directional coupler reflection coefficient and isolation are less than -15 dB, the transmission loss is more than -3.8 dB, the fluctuation range is 0.5 dB and the phase difference is 90°. It satisfies the design requirement of coupler, and can be applied to microwave components to improve the performance.
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Key words:
- harmonic suppression /
- wideband /
- low-pass filter /
- branch section /
- high-and low-impedance line
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表 1 定向耦合器各项指标要求
Table 1. Directional coupler indicators
working frequency/GHz reflection coefficient transmission loss isolation 29~31 |S11|≤-15 dB -3.8 dB≤|Sj1|≤-3 dB, j=2, 3 |S41|≤-15 dB 表 2 低通滤波器尺寸
Table 2. Dimensions of low-pass filter
w1/mm l1/mm w2/mm l2/mm w3/mm l3/mm 0.5 3.73 0.9 3.35 0.23 7.73 表 3 带有谐波抑制功能的定向耦合器尺寸
Table 3. Dimensions of directional coupler with harmonic suppression function
w1/mm l1/mm w2/mm l2/mm w3/mm l3/mm 0.79 1.41 0.23 2.08 0.25 1.96 -
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