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The HP 360A is a coaxial low pass filter with a 700 MHz cut-off frequency, part of the four-model 360 series that also includes the 360B (1.2 GHz), 360C (2.2 GHz), and 360D (4.1 GHz). Each filter consists of a multi-section coaxial filter housed in a brass tube and terminated in Type N connectors, with one male and one female end to allow direct in-line insertion into a 50 ohm coaxial signal path.
These filters are intended to facilitate microwave measurements by eliminating harmonics generated by the signal source. Specific applications described for the series include use as a spectrum analyzer preselector, slotted-line measurements, checking filter characteristics, and determining receiver response. Used as a preselector with the HP 851A/8551A Spectrum Analyzer, the 360 series permits analysis of signals below the filter cut-off frequency without interference from higher-frequency signals.
Hewlett-Packard spun out its test and measurement business as Agilent Technologies in 1999, and the electronic measurement portion of that business was transferred to Keysight Technologies in 2014. Legacy HP-branded coaxial components such as the 360 series predate those transitions and are encountered today primarily as established equipment from the original HP era.
The HP 360 series is a four-model family of coaxial low pass filters that share a common mechanical and electrical architecture and differ primarily in cut-off frequency. All four models use a multi-section coaxial filter in a brass tube housing with Type N connectors, present a 50 ohm pass band impedance, and reach 50 dB or greater rejection at 1.25 times their respective cut-off frequencies.
The four cut-off frequencies — 700 MHz, 1.2 GHz, 2.2 GHz, and 4.1 GHz — cover the harmonic-suppression and preselection ranges most commonly needed in microwave measurement work. Selection within the family is driven directly by where the fundamental of interest sits and where the harmonics or out-of-band content needing rejection begin.
Each pre-owned 360-series model below is listed on its own product page so cut-off frequency, dimensions, and pricing match the specific filter being ordered. Reach out for current availability and lead time on any of the four cut-off variants.
The 360A is the lowest cut-off frequency model in the series at 700 MHz, with the SWR specification holding below 1.6 to within 100 MHz of cut-off. Among the four models it is also the longest, at 10-7/8 inches (276 mm) overall, reflecting the larger filter sections required to achieve cut-off at the lower frequency.
Beyond cut-off frequency, the most visible differences across the series are the SWR transition region and the physical length. SWR stays below 1.6 to within 100 MHz of cut-off on the 360A and 360B, widening to 200 MHz on the 360C and 300 MHz on the 360D. Overall length is 10-7/8 inches (276 mm) for the 360A and 10-25/32 inches (274 mm) for the 360C, while the 360B and 360D are shorter at 7-7/32 inches (183 mm) and 7-3/8 inches (187 mm) respectively. Outer diameter is 5/8 inch (16 mm) across all four models.
The comparison table that follows lays out cut-off frequency, SWR transition margin, overall length, and outer diameter side by side so the right model can be selected for a given measurement band and mechanical envelope.
| Model | Cut-Off Frequency | Insertion Loss | Rejection |
|---|---|---|---|
| 360B | 1200 MC | Not over 1 db below 0.9 times cut-off frequency | 50 db or more at 1.25 x cut-off frequency |
| 360A | 700 MC | Not over 1 db below 0.9 times cut-off frequency | 50 db or more at 1.25 x cut-off frequency |
| 360C | 2200 MC | Not over 1 db below 0.9 times cut-off frequency | 50 db or more at 1.25 x cut-off frequency |
| 360D | 4100 MC | Not over 1 db below 0.9 times cut-off frequency | 50 db or more at 1.25 x cut-off frequency |
Additional differences in specifications beyond the few shown above are not listed here — see each model's full specifications below.
| Specification | Value |
|---|---|
| Cut-Off Frequency | 1200 MC |
| Insertion Loss | Not over 1 db below 0.9 times cut-off frequency |
| Rejection | 50 db or more attenuation at 1.25 x cut-off frequency; greater than 50 db from 1.25Fc to at least 3.0Fc |
| Impedance | 50 ohms through pass band |
| Standing Wave Ratio | Less than 1.6 to within 100 MC of cut-off |
| Spurious Response | No spurious response up to three times cut-off frequency |
| Connectors | Type N, one male and one female |
| Overall Length | 7-7/32 in. (183 mm) |
| O.D. | 5/8 in. (16 mm) |
| Male Offset (Center Line to End) | 2-1/8 in. (54 mm) |
| Female Offset (Center Line to End) | 2-1/4 in. (57 mm) |
| Shipping Weight | Approximately 2 lbs. (0.9 kg) |
Please review the Manufacturer's Data Sheet to verify published specifications. Feedback on this webpage is always welcome — please reach out to your Test Architect at any time for questions or concerns. Thank you, we truly appreciate you being our customer.
Model No
HP
Condition
Used
Manufacturer
Anritsu
Frequency
110 GHz
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