band-pass filter are obtained as shown in Figure 5(a). Obviously, the band-pass filter behaves well in the pass-band of which the return loss is below À10 dB (from 4.66 to 5.55 GHz). The outband suppression is almost better than 20 dB. The simulated resonant characteristics of the three-cascaded CSRR band-pass filter are obtained as shown in Figure 5(b). As can be seen from Figure 5(b), the return loss of the three-cascaded CSRR bandpass filter throughout pass-band range is below À18 dB, whereas out-band suppression is very high. The three-cascaded CSRR band-pass filter achieves better performance in the passband and obtains higher harmonic suppressions in the stop-band. MEASURED RESULTSTo validate the simulated analysis, two-cascaded and three-cascaded CSRR band-pass filters are designed and fabricated. Figure 6 shows the photograph of two band-pass filters with a substrate of ROGERS 4350B. The measured results of two bandpass filters are showed in Figure 7. Measured results show that: the return loss of two-cascaded CSRR band-pass filter is below À10 dB from 4.61 to 5.50 GHz, while the insertion loss in the stop-band is better than 20 dB; the return loss of three-cascaded CSRR band-pass filter is below À18 dB from 4.81 to 5.44 GHz, while the insertion loss is big in the stop-band. The measured results also show the out-band suppression of the three-cascaded CSRR band-pass filter is high and the pass-band performance of the three-cascaded CSRR band-pass filter is excellent. The measured results almost comply with the simulated results and only a small frequency offset and a different insertion loss is due to fabrication tolerance. CONCLUSIONSIn this article, band-pass filters using CSRR are proposed. Twocascaded and three-cascaded CSRR band-pass filters are designed, fabricated and measured. The measured results have shown good agreement with the simulated results. Two-cascaded and three-cascaded CSRR band-pass filters have advantages of compact size, low insertion loss, excellent pass-band performance, and high out-band suppression. This structure can be also used in diplexer and other microwave devices.ABSTRACT: We report the heterodyne generation of a narrow radiofrequency carrier by the beat of the signal of a bimodal fiber laser. The bimodal operation of the designed multiple-cavities-filter-based laser is presented, as well as the measured narrow microwave tone, suitable for modern microwave photonics links. V C 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:451-454, 2012; View this article online at wileyonlinelibrary.com.

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Dynamic gain fluctuations in a ring

The generation and detection of EHF microwave signals through the photomixing of two independent CW laser sources at commercial gallium-arsenide antennas is presented as a versatile technique for short range EHF communications. More than to eliminate further amplification before the irradiating antenna, the proposed technique is able to generate MMW signals at the EHF range with a maximum strength difference of 10 dB through the full range.

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