A network-analyser calibration method for accurate measurement of the reflection coefficients of monopolelike antennas

✍ Scribed by M. D. Migliore; D. Pinchera

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 136 KB
• Volume: 47
• Category: Article
• ISSN: 0895-2477
• DOI: 10.1002/mop.21161

✦ Synopsis

the ACPS-ring magic-T. The maximum amplitude imbalance of the former is about 1.05 dB and occurs around the high end of the frequency band, while that of the latter is 0.82 dB and also located in the high end. This power-level difference at the high-frequency region is mainly due to the fabrication tolerance, resulting in an imbalance of the characteristic impedances of the branches split from E-or H-arm. Figure 7 shows the measured phase imbalances for the 180°out-phase and in-phase operations. The maximum phase imbalance of the difference mode is about 1.7°over the frequency range of 2-6.4 GHz. The maximum phase difference of the sum mode is about 3.1°over the same frequency range. Figure 8 shows the measured and simulated isolations between E-and H-port and those between ports 1 and 2. The measured isolation between E-and H-ports is larger than 25 dB over the frequency range 2-6.4 GHz. The isolation between ports 1 and 2 is larger than 13 dB in the same frequency range. Not shown here (for the purpose of conciseness), the maximum amplitude and phase imbalance of the difference mode for the CPW-ring magic-T are 0.8 dB and 4.6°, respectively, and they are 0.74 dB and 2.9°for the sum mode, all in the acquired bandwidth (2.2-6.8 GHz). The corresponding isolations between E and H ports are more than 28 dB, and those between ports 1 and 2 are larger than 15 dB.

4. CONCLUSION

This paper has presented the experimental and simulated results of the proposed uniplannar magic-T couplers, composed of an ACPSring or CPW-ring structure, which has a fairly good power-dividing level and small amplitude and phase imbalances. The circuits achieved a very good wideband property (2-6.4 GHz for the ACPS-ring magic-T and 2.2-6.8 GHz for the CPW-ring magic-T). With the advantages of broadband operation, simple structure, low cost, and an easy design procedure, these uniplanar ACPS-ring and CPW-ring magic-T couplers can be easily integrated with solidstate devices and MICs, and find many applications in microwave hybrid or MMIC circuits.