CAVITY FILTER DESIGN

COMPROD has one of the most rugged, high-quality cavity filter construction with our proven, temperature-compensated cavities. The flexibility of four versions of filters, BANDPASS, NOTCH, PASS-REJECT, and X-PASS, available in 2 inch, 4 inch, 6.625 inch and 10 inch cavities, permits any system to be designed for maximum performance and efficiency. The following filters can be achieved by swapping the loops, while maintaining the same cavity, using only 6.625 inch and 10 inch cavities.

1. BANDPASS CAVITY FILTER – Passes one narrow band of frequencies and attenuates all others with increasing attenuation above and below the pass frequency. The adjustable selectivity characteristics (rotatable loops) allow a trade-off between insertion loss (0.5-3.0 dB) and selectivity. This filter is ideal when the interfering frequencies are not known to any degree of accuracy or when very high broadband filtering is required.

2. NOTCH – Passes a relatively wideband of frequencies, while rejecting a very narrow band of frequencies. Notch depth is variable from 15-25 dB. Both the pass and notch frequencies must be known. The wide pass band can be an advantage when filtering multiple channel transmitters and receivers. This filter is ideal for very close separations (70-200 KHz) in VHF and (200-400 KHz) in UHF.

3. PASS-REJECT – Passes and rejects a relatively narrow band of frequencies. This filter has the greatest notch depth when compared to other types. Notch depth is adjustable, but is referred to a pass band insertion loss (0.3 dB or 0.6 dB typical). This filter type is best for moderately close to wide separations (200 kHz and greater) in VHF and (400 kHz and greater) in UHF.

4. X-PASS – A special type of filter for expandable multicoupler/combiner applications. Characteristics are identical to a bandpass filter, but have a third port for coupling to other channels. This filter is ideal for close frequency spacing with extremely low losses, acting as a hybrid combiner/multicoupler, yet is extremely flexible and expandable; 1-21 and over channel capabilities.

All of COMPROD 6.625 inch and 10 inch filters have two-hand movable tuning rods (a coarse and a fine) for a 35 percent faster tuning capability. Using adjustable silver-plated coupling loops and calibration index label, it easily facilitates setting cavity insertion loss as required for each application.

The combination of a heavy-gauge aluminum outer conductor, thick heliarc-welded cavity top plates, heavy silver plating on micro finished tuning assemblies, and Invar-based temperature compensation material results in constant performance levels and long-term reliability. Cavity and isolator connectors are Type N female, with silver-plated brass bodies and gold-plated center contacts. Thru-line cable assemblies are made with high-quality connectors and RG-393B/U Teflon or RG-214/U cable, to provide excellent intermodulation performance at high system power levels. Gold-plated cable connector center contacts are soldered to the cable, and the dual shield is securely crimped to the connector barrel using pneumatic fixtures and precision dies. These attributes contribute to the high quality products that our clients have become accustomed to.

For more information on COMPROD X-Pass, Combiners, Multicouplers, Duplexers, Pass Reject, BandPass, or Notch filters, contact our Technical Support team at 1.800.603.1454 or 1.450.641.1454.