• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.2 s.93
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• pp.134-138
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• 2005

In this paper, we have developed a new type of the microwave phase conjugator for the active retrodirective antenna array. The circuit topology is consisted of a 2-port structure to avoid the complexity of LO and RF signal combination and matching, using the cascade connection of two single-ended mixers. The operating frequencies are 4.0 GHz, 2.01 GHz and 1.99 GHz for LO, RF, and IF, respectively. Conversion loss is measured to be -7 dB and 1-dB compression point 15 dBm with the LO power of 9 dBm. For the most important parameter, the isolation between RE leakage and IF signal is as high as 25 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.9
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• pp.907-915
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• 2002

In this paper, a compact digital phase shifter to be used an active phased array antenna system for satellite communications was proposed. The even and odd mode analysis for a given reflection-type phase shifter, which uses a folded hybrid coupler as a base element, was performed and the design parameters were derived. Also, to verify experimentally the electrical performances of the proposed structure, X-band 4-bit digital phase shifter was designed and fabricated using Teflon soft substrate $({\varepsilon}_r; =\;2.17)$. Its circuit size was less than 3.5 cm $\times$ 3.0 cm, and it exhibited at least 50 % size reduction as compared with the conventional unfolded configuration. The experimental results of the fabricated phase shifter showed that the average insertion loss and insertion loss variation were less than 3.5 dB, $\pm$ 0.6 dB within the operating band, 7.9 ~ 8.4 GHz, respectively. And, input and output return loss were more than 10 dB, respectively. Also, the phase response of the phase shifter showed 4-bit operation with $\pm$3$^{\circ}$ rms phase error.