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- 实验方案
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COUPLED LINE RAT-RACE COUPLER WITH WIDE ADJUSTABLE POWER DIVIDING RATIO AND UNCROSSED INPUT/OUTPUT PORTS
摘要： A novel rat-race coupler with wide adjustable range of power-dividing ratio and uncrossed input/output ports is presented by using coupling adjustable trans-directional (TRD) coupled lines, parallel coupled lines and a 180? phase shifting line. Wide adjustable range of power-dividing ratios is accomplished by varying the coupling of the TRD coupled lines. Moreover, with the combination of the TRD coupled lines and parallel coupled lines, the input and output ports of the rat-race coupler are uncrossed. The structure of the proposed rat-race coupler is analyzed, and the design equations are derived. As an example to validate the feature of the proposed rat-race coupler, a prototype operating at 1.6 GHz is devised, fabricated and measured. The measured results show that the designed coupler has a wide adjustable range (?7 ～ 15 dB) of power dividing ratio with a controlled voltage range of 3.3 to 13.5 V.
关键词： rat-race coupler,parallel coupled lines,TRD coupled lines,uncrossed input/output ports,180? phase shifting line,adjustable power-dividing ratio
更新于2025-09-12 10:27:22
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Ultra-Compact Tunable Filtering Rat-Race Coupler Based on Half-Mode SIW Evanescent-Mode Cavity Resonators
摘要： In this paper, for the first time, an ultra-compact frequency-tunable filtering rat-race coupler based on half-mode evanescent-mode (EVA) cavity resonators is presented. Employing EVA cavity resonators in the coupler design yields attractive characteristics, such as a wide tuning range and a wide spurious-free range, while also adding filtering functionality to the device. The presented coupler is synthesized as a two pole bandpass filter using the coupling matrix method. Then, the coupling coefficients are mapped to a coupler topology. Design, simulations, and experimental validation are presented. The implemented rat-race coupler has a very compact size [0.14λg × 0.14λg (λg at 885 MHz)] achieving a 92% miniaturization in the structure footprint compared to the conventional planar one. The coupler has an 86% tuning range ranging between 0.885–1.65 GHz. Throughout the tuning range, the coupler shows an equal power splitting ratio and filtering profile with a measured insertion loss and 3-dB fractional bandwidth between 5 and 4.2 dB and 6.8% and 8%, respectively. The measured isolation is better than 30 dB. In addition, the coupler has a measured spurious-free range of 10.2 fo (at the lowest frequency) to 5.45 fo (at the highest frequency).
关键词： rat-race coupler,tunable resonators,Evanescent-mode (EVA) cavity,tunable coupler,half-mode
更新于2025-09-11 14:15:04
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Theory and Design of a Retrodirective Rat-Race-Based RFID Tag
摘要： Movement towards mm-wave backscatter communications in radio-frequency identification (RFID) systems necessitates seeking designs that compensate for the path loss introduced by the radio channel. A viable, simple, and power-efficient solution is to equip RFID tags with retrodirective arrays, which guarantee reflection with maximal gain in the direction of incidence. In this paper, we build upon a previous work to design and implement an original retrodirective tag in which its feeding network is a properly-terminated rat-race coupler. We start by deriving the required terminations that ensure retrodirectivity. Then, we build a retrodirective tag and experimentally compare its radar cross section to that of a single-antenna tag. The measurements reveal that the radar cross section of the proposed retrodirective tag is, on average, approximately 6 dB more than that of a single-antenna tag while both tags have the same field-of-view. From the promising results in this paper, the proposed design is a potential candidate for next-generation microwave and mm-wave RFID tags because it is compatible with low-power reflection amplifiers (e.g., tunnel diodes), it can implement multiple modulation schemes without changing the circuit layout, and it can be implemented using only a single RF switch.
关键词： multi-modulation RFID tags,Retrodirective arrays,rat-race coupler
更新于2025-09-09 09:28:46