RF Electronics Chapter 7: RF Filters Page 268
2022, C. J. Kikkert, James Cook University, ISBN 978-0-6486803-9-0.
A Change of E
r
from 3.38 to 3.53 gives a 2% change in centre frequency. The circuit and
EM simulations centre frequencies will thus differ by 2%, as shown in figure 7.51 (for
same E
r
) and figure 7.94 (different E
r
). The difference between the desired and measured
centre frequency of the circuit in figure 7.46 is 30 MHz (3%), as shown in figure 7.51.
For the filter in figure 7.83, it is 5 MHz (0.5%), as shown in figure 7.87. The filter in
figure 7.46 uses 1.75mm wide resonators and the filter in figure 7.83 uses 3mm wide
resonators. The wider resonators result in a lower insertion loss and less impedance errors
due to inaccuracies in milling or etching of the PCB.
Figure 7.94. Passband Frequency response of Circuit and EM simulations of the hairpin filter.
Figure 7.95. Passband Frequency response of Circuit and EM simulations of the hairpin filter.
RF Electronics: Design and Simulation
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