Coaxial Suspension Line Low Pass Filter
Coaxial Suspension Line Low Pass Filter suppresses high-frequency harmonics while maintaining low insertion loss in RF systems. Ideal for microwave transmitters, communication infrastructure and radar electronics.
High-Performance Suspension Line Low Pass Filters for Spurious Rejection
AO Microwave’s high-precision coaxial suspension line low pass filters (Suspended Substrate Stripline - SSS) are engineered to transmit low-frequency signals with minimum loss while providing high rejection of out-of-band harmonics up to 40 GHz. Built with a thin low-loss Rogers substrate suspended symmetrically inside a machined aluminum cavity, these filters achieve high stopband rejection and cutoff sharpness. Our suspension line low pass filters deliver low insertion losses (typically < 0.5 dB in the passband), an input VSWR of < 1.25:1, and a wide stopband rejection extending up to several times the cutoff frequency.
By utilizing the air dielectric of the suspended structure, our SSS low pass filters minimize conductor loss, allowing for steep roll-off characteristics. They are critical for harmonic suppression in broadband transmitters, synthesizer filtering, and mixer spurious rejection.
| Part No | Frequency/GHz | VSWR (Max) | IL/dB (Max) | Stopband Rejection/dB (Min) | Size/mm |
|---|---|---|---|---|---|
| AO2.5M-CSLPF-SK | DC-2.5MHz | 1.5 | 0.8 | 50dB@5-50MHz | 40.4x12x10 |
| AO5M-CSLPF-SK | DC-5MHz | 1.5 | 1 | 50dB@8-50MHz | 40.4x12x10 |
| AO10M-CSLPF-SK | DC-10MHz | 1.5 | 1 | 50dB@13-150MHz | 40.4x12x10 |
| AO1G-CSLPF-SK | DC-1 | 2 | 1 | 50dB@1.25-3GHz | 38x40x10 |
| AO1G-CSLPF-SK | DC-1 | 2 | 1 | 50dB@1.5-5GHz | 75x60x10 |
| AO1.2G-CSLPF-SK | DC-1.2 | 1.5 | 1 | 60dB@1.8-8GHz | 50x17x10 |
| AO2G-CSLPF-SK | DC-2 | 1.5 | 1 | 50dB@2.3-4GHz | 38x27x10 |
| AO2.4G-CSLPF-SK | DC-2.4 | 1.7 | 2 | 58dB@3-18GHz | 65x14x10 |
| AO3G-CSLPF-SK-C1 | DC-3 | 1.5 | 1 | 50dB@3.45-7GHz | 43.2x23.5x10 |
| AO3G-CSLPF-SK-C2 | DC-3 | 1.5 | 1.5 | 60dB@3.5-20GHz | 80x28x10 |
| AO3.2G-CSLPF-SK-C1 | DC-3.2 | 1.5 | 1 | 40dB@3.8-18GHz | 64x23.5x10 |
| AO3.2G-CSLPF-SK-C2 | DC-3.2 | 1.5 | 1.5 | 60dB@3.6-20GHz | 80x28x10 |
| AO3.5G-CSLPF-SK | DC-3.5 | 1.5 | 1.5 | 40dB@3.8-518GHz | 64x23.5x10 |
| AO3.87G-CSLPF-SK | DC-3.87 | 1.7 | 2.5 | 30dB@4.32GHz | 70x14x10 |
| AO4G-CSLPF-SK | DC-4 | 2 | 1 | 50dB@4.7-8GHz | 43.2x23x10 |
| AO5G-CSLPF-SK | DC-5 | 2 | 1 | 45dB@5.8-10.5GHz | 43x18.8x10 |
| AO5.325G-CSLPF-SK | DC-5.325 | 1.5 | 1.5 | 30dB@5.925GHz | 50x25x10 |
| AO5.5G-CSLPF-SK | DC-5.5 | 2 | 3 | 60dB@6-20GHz | 65x20x10 |
| AO6G-CSLPF-SK | DC-6 | 2 | 1 | 45dB@6.8-10.5GHz | 43x18.8x10 |
| AO6.5G-CSLPF-SK | DC-6.5 | 1.8 | 1 | 30dB@8-15GHz | 30x15x8 |
| AO7G-CSLPF-SK | DC-7 | 2 | 1 | 48dB@7.8-11GHz | 43x18.8x10 |
| AO8G-CSLPF-SK-C1 | DC-8 | 2 | 1 | 50dB@8.8-20GHz | 43x18.8x10 |
| AO8G-CSLPF-SK-C2 | DC-8 | 2 | 1.2 | 50dB@9-18GHz | 45x20x10 |
| AO8G-CSLPF-SK-C3 | DC-8 | 1.5 | 1.2 | 40dB@8.9-16GHz | 27x16x10 |
| AO9G-CSLPF-SK | DC-9 | 2 | 1 | 50dB@15-22GHz | 24x18.8x10 |
| AO10G-CSLPF-SK | DC-10 | 1.7 | 1 | 30dB@13.2GHz | 29x10.16x6.35 |
| AO10G-CSLPF-SK-C2 | DC-10 | 2 | 1 | 35dB@11GHz | 47x18.8x10 |
| AO10G-CSLPF-SK-C3 | DC-10 | 1.7 | 0.5 | 20dB@12GHz | 24x18.8x10 |
| AO10G-CSLPF-SK-C4 | DC-10 | 1.8 | 1 | 30dB@13-40GHz | 30x15x8 |
| AO11G-CSLPF-SK | DC-11 | 1.8 | 2 | 45dB@12-24GHz | 60x20x10 |
| AO11.7G-CSLPF-SK | DC-11.7 | 1.7 | 2 | 50dB@12.7-13.45GHz | 55x18.8x10 |
| AO12G-CSLPF-SK | DC-12 | 1.7 | 1 | 70dB@14-19GHz | 30x18.8x10 |
| AO13G-CSLPF-SK | DC-13 | 1.8 | 1.5 | 55dB@15.2-40GHz | 40x15x10 |
| AO14G-CSLPF-SK | DC-14 | 1.8 | 1 | 45dB@20-40GHz | 26x13x8 |
| AO16G-CSLPF-SK | DC-16 | 2 | 1.5 | 50dB@16.8-24GHz | 28x18.8x10 |
| AO17G-CSLPF-SK | DC-17 | 2 | 1.5 | 50dB@30-33GHz | 28x18.8x10 |
| AO18G-CSLPF-SK | DC-18 | 1.7 | 1 | 15dB@20GHz | 28x18.8x10 |
| AO18G-CSLPF-SK-C1 | DC-18 | 2 | 2 | 50dB@18.8-19.5GHz | 28x15x10 |
| AO18G-CSLPF-SK-C3 | DC-18 | 2 | 1.2 | 45dB@28-40GHz | 22x13x8 |
| AO18G-CSLPF-SK-C4 | DC-18 | 2 | 1.5 | 35dB@19-28GHz | 23x16x6 |
| AO20G-CSLPF-SK-C1 | DC-20 | 2 | 1.2 | 50dB@22GHz | 30x18.8x10 |
| AO20G-CSLPF-SK-C2 | DC-20 | 2 | 2 | 25dB@23-40GHz | 19x15x10 |
| AO20G-CSLPF-SK-C3 | DC-20 | 2 | 1.5 | 75dB@24-44GHz | 30x14x10 |
| AO20G-CSLPF-SK-C4 | DC-20 | 1.8 | 1.5 | 70dB@24GHz | 45x13x10 |
| AO25G-CSLPF-SK-C1 | DC-25 | 1.7 | 1.5 | 40dB@28-40GHz | 27x16x10 |
| AO25G-CSLPF-SK-C2 | DC-25 | 2 | 2 | 40dB@28-40GHz 70dB@30-44GHz | 58x13x11 |
| AO26G-CSLPF-SK | DC-26 | 1.7 | 1.5 | 30dB@28GHz | 27x16x10 |
| AO33G-CSLPF-2.92K | DC-33 | 2 | 3 | 25dB@37-50GHz | 13x15x10 |
| AO40G-CSLPF-2.92K | DC-40 | 2 | 2 | 50dB@70GHz | 15x15x10 |
| AO50G-CSLPF-2.4K | DC-50 | 2.5 | 2 | 20dB@60GHz | 15x15x10 |
Stepped Impedance Designs in Suspension Line Low Pass Filters
Suspension line low pass filters operate by utilizing high-impedance and low-impedance line sections in series. High-impedance narrow lines act as series inductors, while low-impedance wide sections behave as shunt capacitors, establishing a low pass filtering network.
To achieve high out-of-band rejection and steep cutoff sharpness, the steps between these sections must be precisely managed. AO Microwave utilizes stepped impedance matching networks printed on low-loss suspended substrates. This design minimizes capacitive and inductive mismatches near the cutoff frequency, ensuring a flat passband and steep roll-off characteristics.
Target Applications & Operational Advantages
By providing low insertion loss and high mechanical durability, our suspension line low pass filters enable reliable performance in active systems:
Harmonic Suppression in Transmitters
Function: Suppresses high-frequency harmonics at the output of active power amplifiers.
Advantage: Sharp cutoff selectivity and low passband insertion loss (<0.5 dB) prevent harmonic emissions from degrading system performance.
Broadband Synthesizer Filtering
Function: Filters out spurious signals and reference harmonics in broadband frequency synthesizers.
Advantage: Exceptional stopband rejection extending up to several times the cutoff frequency ensures clean LO signals.
Mixer Spurious Rejection
Function: Placed at the IF output of mixers to suppress high-frequency LO and RF leakage.
Advantage: High out-of-band rejection and stable passband VSWR prevent unwanted leakage from degrading receiver sensitivity.
Suspension Line Low Pass Filter FAQs
Need high-performance Suspension Line Low Pass Filters?
Specify your cutoff frequency, stopband range, rejection depth, average power, and connector interface — we'll quote in 24 hours.
