Coaxial Band Stop Filter
Coaxial Band Stop Filter suppresses unwanted interference frequencies while allowing other signals to pass. Used in RF transmitters, communication networks, radar systems and microwave signal processing applications.
Precision Coaxial Band Stop Filters for Deep Interfering Signal Suppression
AO Microwave’s high-rejection coaxial band stop filters (notch filters) are designed to suppress specific narrow-band jammers or interfering carriers while allowing adjacent passband signals to pass with minimum loss. Built with precision-machined aluminum and copper cavities, these notch filters feature multiple resonant cavities coupled inductively or capacitively to a common coaxial transmission line. Operating up to 40 GHz, our band stop filters achieve an outstanding notch rejection depth of typically > 50 to 60 dB, low passband insertion loss (typically < 0.5 dB), and a stable passband VSWR of < 1.25:1.
By utilizing precisely tuned, temperature-compensated Invar resonators, our notch filters ensure stable jammer suppression. They are critical for co-site transceiver isolation, electronic warfare receiver protection, and high-frequency communication jammer suppression.
| Part No | Frequency/GHz | VSWR (Max) | IL/dB (Max) | Rejection/dB (Min) | Low Passband/GHz | High Passband/GHz |
|---|---|---|---|---|---|---|
| AO0.88G0.96G-CBSF-SK | 0.88-0.96 | 1.5 | 1.5 | 20 | DC-0.68 | 0.978-2.3 |
| AO1.53425G1.69875G-CBSF-SK | 1.53425-1.69875 | 1.8 | 0.8 | 50 | DC-1.2 | 2.1-4.2 |
| AO2.166G2.394G-CBSF-SK | 2.166-2.394 | 1.8 | 0.8 | 50 | DC-1.7 | 2.85-5 |
| AO2.935G3.465G-CBSF-SK | 2.935-3.465 | 1.7 | 1 | 50 | DC-1.9 | 4.5-7 |
| AO5.225G5.775G-CBSF-SK | 5.225-5.775 | 1.7 | 1 | 95 | DC-4.1 | 6.9-11.55 |
| AO7.867G7.881G-CBSF-SK | 7.867-7.881 | 2 | 2 | 50 | DC-7.72 | 8.1-12 |
| AO24G24.5G-CBSF-SK | 24-24.5 | 2 | 3 | 40 | DC-23.5 | 25-40 |
Steep Roll-off & High-Q Cavity Coupling in Notch Filters
Coaxial band stop (notch) filters operate by coupling resonant cavities to a common transmission line, absorbing or reflecting a specific narrow frequency band. To achieve steep roll-off—allowing the passband to remain low-loss right next to the deep stopband—the coupling structures must be highly precise.
AO Microwave designs its cavity notch filters with high-Q cylindrical resonators coupled capacitively to the main coaxial line. By using computerized 3D electromagnetic simulations to optimize the coupling probe dimensions, we achieve a very sharp roll-off. This allows adjacent channels to pass with minimal loss while suppressing the target jammer frequency.
Target Applications & Operational Advantages
By providing deep notch suppression and low passband insertion loss, our coaxial band stop filters secure critical active communication systems:
Co-Site Transceiver Isolation
Function: Placed at the receiver input to block a strong local transmit signal from blinding or damaging the receiver LNA.
Advantage: Exceptional notch rejection depth (>50 dB) isolates co-site transmitters, maintaining receiver sensitivity.
Electronic Warfare Receiver Protection
Function: Filters out known fixed-frequency interfering signals before wideband signal processing.
Advantage: High out-of-band passband performance maintains signal integrity across the remaining monitored spectrum.
Cellular & GPS Jammer Suppression
Function: Blocks strong out-of-band cellular or GPS jammer signals in defense networks.
Advantage: Precise, narrow-band notch profiles suppress interference with minimal impact on adjacent operating channels.
Coaxial Band Stop Filter FAQs
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