Читать книгу Handbook of Microwave Component Measurements - Joel P. Dunsmore - Страница 51

For many design and measurement applications, the circuit of interest is embedded in a PC board. There are many types and styles of PC board launches, which typically have an SMA connector on one end and PC board contacts at the other, as well as miniature versions such as the QMA connector. These can come in edge launch as well as right angle, and their performance depends greatly upon the mounting pattern on the PC board trace. These can be difficult to characterize because only one end is available in a standard connector. An example of a common PC board launch is shown in Figure 1.29. Measurement techniques for these devices, as well as methods to remove their effects from the measurement of on‐board PC components, are discussed in Chapter 11.

Figure 1.29 PC board SMC launches.

Connectors designed for coaxial‐cables provide similar challenges, as the cable to which they are attached affects the quality of the connection, and the common practice of attaching two connectors to each end of cable makes it difficult to separate the effects of one from the other. Time‐domain techniques can be applied to remove these unwanted effects, as described in Chapter 5.