the corresponding value of Q decreases rapidly with increasing b/a. This tendency indicates the significance of selecting dimension has large as possible. Figure 5 and Fig. 6 show the sensitivity Q and the shortening coefficient 17 as functions oidia and sla, respectively. Since the cavity is cutoff, it is expected that the sensitivity Q can be improved by decreasing the depth of the antenna s. However, Fig. 6 illustrates the saturating tendency of Q as s decreases. This tendency can be interpreted as follows. For the case of large 5, the aperture electric field is weak and the radiation resistance becomes also small. For a small value of 5, the distribution of electric field is not uniform as shown in Fig. 7 and only the field in the vicinity of the driving point is strong which yields rather a small radiation resistance and a large value of Q.
RkJQdWJsaXNoZXIy MTU5NjU0Mg==