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This paper proposes a compact bandpass filter using a folded ring resonator, which occupies an area, one-quarter the size of a conventional ring resonator. For the filter design, circuit modeling is used to derive the coupling coefficients between the even- and odd-mode resonances of the proposed resonator with the perturbation stub. The validity of the proposed filter is demonstrated by designing and fabricating a two-pole bandpass filter with a 100 MHz bandwidth at the central frequency of 2.45 GHz [ABSTRACT FROM AUTHOR]

This study analyzes the propagation of the path losses between Jeju-do and Jin-do transceivers located in the coastal areas of Korea using the Advanced Refractive Prediction System(AREPS) simulation software based on the actual coastal weather database. The simulated data is used to construct a duct map according to the altitude and thickness of the trap. The duct map is then divided into several regions depending on the altitude parameters of Tx and Rx, which can be used to effectively estimate the abnormal wave propagation characteristics due to duct occurrence in the Jeju-do coastal area. To validate the proposed duct map, two representative atmospheric index samples of the weather database in May 2018 are selected, and the simulated path losses using these atmospheric indices are compared with the measured data. The simulated path losses for abnormal conditions at the Rx point at Jeju-do are 167.7 dB and 192.3 dB, respectively, which are in good agreement with the measured data of 164.4 dB and 194.9 dB, respectively. [ABSTRACT FROM AUTHOR]

In this paper, we proposed a multi-function conversion block for microwave receiver. The proposed multi-function conversion block is composed of a broadband voltage controlled oscillator and a dual-mode mixer. Depending on whether the bias voltage is supplied, the first IF(Intermediate Frequency) output frequency(4,595 MHz/ 6,045 MHz) needed in microwave receiver is converted to 720 MHz and the another IF output frequency(720 MHz) for receiving Ku-band has the multi-functional operations of the dual mode that are bypass and attenuation without frequency conversion. Implementation and measurement results show that each intermediate frequency has conversion loss characteristic according to the LO power. The LO power conversion loss of 4,595 MHz at the LO levels from 2 dBm to 4 dBm is 13 dB, another of 6,035 MHz is 12 dB and the other of 720 MHz is 7.0 dB. [ABSTRACT FROM AUTHOR]