Coaxial Suspension Line Bandpass Filter
Coaxial Suspension Line Bandpass Filter provides high-Q filtering performance with low insertion loss and excellent frequency selectivity. Widely used in microwave communication systems, radar electronics and RF front-end modules.
High-Performance Suspension Line Bandpass Filters for Wideband RF Systems
AO Microwave’s high-precision coaxial suspension line bandpass filters (Suspended Substrate Stripline - SSS) are engineered to deliver low-loss, ultra-wideband filtering up to 40 GHz. Built with a thin low-loss Rogers laminate suspended symmetrically inside a precision-machined aluminum housing—leaving air cavities above and below—these filters achieve a much higher Q-factor than standard microstrip. Our suspension line bandpass filters deliver exceptional passband flatness, low insertion losses (typically < 0.8 dB over multi-octave bands), and stable input VSWR of < 1.35:1.
By utilizing the air dielectric of the suspended structure, our SSS filters minimize dielectric loss, allowing for extremely wide passbands (e.g., 2 to 18 GHz) with sharp out-of-band rejection. They are critical for wideband electronic warfare (EW) receivers, multi-octave signal monitoring, and compact airborne instrumentation.
| Part No | Frequency/GHz | VSWR (Max) | IL/dB (Max) | Stopband Rejection/dB (Min) | Size/mm |
|---|---|---|---|---|---|
| AO2G6G-CSBPF-SK | 2-6 | 2 | 2 | 60dB@DC-1.5GHz 25dB@6.5-18GHz | 45x20x10 |
| AO2G18G-CSBPF-SK | 2-18 | 2 | 2 | 60dB@DC-1.5GHz 40dB@18.75-40GHz | 70x20x10 |
| AO3G18G-CSBPF-SK | 3-18 | 2 | 2 | 55dB@DC-2.3GHz 40dB@18.75-40GHz | 66x20x10 |
| AO4G12G-CSBPF-SK | 4-12 | 2 | 1 | 50dB@DC-3.4GHz 50dB@14GHz | 54x30x10 |
| AO10G14G-CSBPF-SK | 10-14 | 2 | 1 | 50dB@DC-7GHz 50dB@18.9GHz | 24x13x10 |
| AO14G18G-CSBPF-SK | 14-18 | 2 | 2 | 50dB@DC-9.3GHz 40dB@20GHz | 29x13x10 |
| AO18G22G-CSBPF-SK | 18-22 | 2 | 2 | 30dB@DC-16GHz 45dB@24-30GHz | 29x13x10 |
| AO20G26G-CSBPF-SK | 20-26 | 2 | 1.5 | 30dB@DC-18GHz 40dB@32GHz | 29x13x10 |
| AO18G35G-CSBPF-2.92K | 18-35 | 2 | 3 | 50dB@DC-16GHz 50dB@43GHz | 28.3x18x10 |
| AO18G41G-CSBPF-2.92K | 18-41 | 2 | 3 | 50dB@DC-16GHz 50dB@43GHz | 28x18x10 |
The Physics of Suspended Substrate Stripline (SSS) Technology
Suspended Substrate Stripline (SSS) technology bridges the gap between plane microstrip and bulky cavity structures. In SSS, a thin dielectric card with printed conductive patterns is suspended symmetrically inside a machined metal channel, leaving air cavities both above and below.
Because the electromagnetic field travels primarily through the air dielectric rather than the substrate material, SSS minimizes dielectric losses. This suspended structure provides a much higher Q-factor than standard microstrip, while remaining far more compact and lightweight than traditional cavity filters. This allows for extremely wideband passbands with sharp, low-loss transitions.
Target Applications & Operational Advantages
By providing low insertion loss and high mechanical durability, our suspension line bandpass filters enable reliable performance in active systems:
Wideband Electronic Warfare (EW) Receivers
Function: Filters incoming wideband signals across multi-octave ranges in defense receivers.
Advantage: Ultra-wideband passbands (e.g., 2 to 18 GHz) allow for broad spectral monitoring with minimal insertion loss (<0.8 dB).
Compact Airborne Instrumentation
Function: Provides bandpass filtering in space-limited airborne and UAV radar pods.
Advantage: Lightweight aluminum housings and flat SSS construction help meet strict mass and physical volume budgets.
Multi-Octave Signal Monitoring
Function: Filters out-of-band signals in broadband test and measurement setups.
Advantage: High out-of-band rejection and excellent passband flatness ensure highly accurate signal analysis.
Suspension Line Bandpass Filter FAQs
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