(12) BANDPASS
The Bandpass cavity passes one narrow band of frequencies and attenuates all others with increasing attenuation above and below the pass frequency. It is equivalent to a parallel-tuned circuit and is most often used for general transmitter spurious clean-up or a sharpening of a single receiver front end selectivity with or without amplification. TX RX bandpass cavities (4", 6", 8” and 10") have adjustable selectivity characteristics (rotatable loops) to allow a trade-off between insertion loss (0.5--3.0 dB) and selectivity. Maximum power handling is typically determined by insertion loss setting.
(12) SERIES NOTCH® The Series-Notch® passes a relatively wide band of frequencies while rejecting a very narrow band of frequencies. It is equivalent to a series-tuned circuit. Notch depth is variable from 15-25 dB. Pass and notch frequencies must be known so that the optimum loop assembly can be used. This is the best filter for very close separations (200-400 KHz) in UHF applications.
(23) VARI-NOTCH® The Vari-Notch® design passes a relatively narrow band of frequencies and rejects (notches out) a relatively wide frequency band. Equivalent to a combination series-tuned and parallel-tuned circuit, this filter has a greater notch depth than the Series- Notch® design. The notch depth is adjustable but varies with passband insertion loss (0.3dB or 0.6dB typical) and the difference between pass and notch frequencies. Vari-Notch® is ideal for moderately close to wide separations (400 KHz and greater) in UHF applications.
