Lab and field validation across the usable band up to 3 GHz demonstrates why connector PIM and insertion loss matter for modern wireless networks. This report validates the TC-SPO375-NM-RA-LP performance target for low PIM and insertion loss using controlled lab instrumentation plus representative field deployments. The test scope covered two-tone PIM up to typical carrier power levels, S-parameter sweeps to 3 GHz and beyond, environmental cycling, and multiple mate/demate cycles to quantify repeatability. Primary takeaways include measured PIM margins versus common project thresholds, insertion-loss behavior across the band, installation sensitivities, and clear pass/fail criteria for site acceptance.
This introduction sets expectations: results are traceable to calibrated PIM analyzers, VNAs, and documented calibration reference planes. The next sections present product context, detailed lab methodology, processed data with uncertainty statements, field validation outcomes, a competitive benchmark, and practical engineering checklists for reliable low-PIM installations.
Point: The TC-SPO375-NM-RA-LP is a right-angle N-type male solder-attachment connector designed for low-loss, low-intermodulation applications on SPO-375/SPP-375 cable systems and similar low-PIM coax. Evidence: mechanical form factor is right-angle N-male with solder tail for 3.5–3.75 series cables; materials typically include silver- or gold-plated center contacts and corrosion-resistant outer bodies; electrical ratings support operation beyond 3 GHz with typical VSWR under 1.2:1 in many assemblies. Explanation: in practice, this model is specified where tight RF budgets and PIM-sensitive DAS or macro sites require connector-level PIM below project thresholds while maintaining insertion loss at a few tenths of a dB per connection. The connector is intended for outdoor and indoor wireless use where low PIM and low insertion loss are both critical to link budget and interference control.
Point: Poor PIM and excessive insertion loss directly degrade network KPIs. Evidence: passive intermodulation appearing in the receive band can raise effective noise floor, reduce CINR, and cause coverage holes; insertion loss reduces available transmit/receive margin and can force higher amplifier power or closer cell spacing. Explanation: for macro sites, a conservative acceptance target is PIM ≤ -150 dBc (measured at two-tone combined power typical of +43 dBm per tone) and insertion loss per connector below ~0.2 dB at 3 GHz; small cells and DAS often require tighter PIM (≤ -155 dBc) because of closer proximity to receivers and multiple RF paths. Meeting these thresholds preserves cell capacity, reduces dropped calls, and keeps power budgets predictable.
Point: Tests were organized to compare datasheet claims to measured behavior under representative stresses. Evidence: the matrix included 2–3 sample assemblies in lab for detailed PIM sweeps from 698 MHz to 3.5 GHz, two-tone tests at example combined power levels of +40 to +46 dBm total, S-parameter sweeps with a calibrated VNA, 10 mate/demate cycles, and environmental conditioning at temperature extremes and humidity. Field validation used two live sites with typical antennas and cable runs to observe before/after installation PIM and link-budget changes. Explanation: acceptance criteria were predefined (PIM threshold and insertion loss ceiling per deployment type) so pass/fail decisions are objective; comparisons include spec vs measured and a short competitor set to show relative performance.
Point: Accurate PIM and insertion-loss assessment requires controlled instrumentation and strict reference-plane management. Evidence: required instruments included a two-tone PIM analyzer capable of at least +46 dBm combined tone power and a noise floor below -160 dBc, a power amplifier to reach target levels, high-quality coaxial loads/couplers rated at test power, and a VNA for S-parameter sweeps. Calibration steps covered port extension to the intended connector face, verification of test-cable loss with a power meter and VNA, and torque-controlled mating using calibrated torque wrenches at manufacturer-recommended values. Explanation: documenting the reference plane and subtracting test-cable loss is essential so reported connector PIM and insertion loss reflect the DUT and not the test-fixture. All calibration artifacts, serial numbers, and date stamps must be recorded to maintain traceability.
Point: The two-tone PIM test defines the primary metric for passive intermodulation. Evidence: recommended procedure set tone frequencies spaced to create third-order intermodulation products inside the band of interest (for example, f1 = 1930 MHz, f2 = 1935 MHz producing 2f1–f2 and 2f2–f1 inside receive bands), combined power example +43 dBm per tone (project-specific power should be used), a dwell/measure time of 10–30 seconds per frequency point, averaging across 3 measurements per mate state, and repeated mate/demate cycles (10–20 cycles) to observe mechanical repeatability. PIM products are reported in dBc relative to tone amplitude; measure and report instrument noise floor and uncertainty (e.g., ±2 dB). Explanation: consistent test parameters and repetition expose intermittent or contact-related PIM; reporting the measurement uncertainty prevents overinterpreting small margins and helps define conservative installation acceptance limits.
Point: S-parameter sweeps quantify insertion loss and return loss across the operating band. Evidence: VNA setup used a calibrated sweep from 400 MHz up to at least 3.5 GHz with 1601 points (or finer as required), connectorized with the same test-cable assemblies used in PIM tests, and temperature-controlled ambient where possible. Measure S21 (insertion loss) and S11 (return loss/VSWR), save data in Touchstone (.s2p) and CSV formats, and produce plots of insertion loss vs frequency and VSWR vs frequency. Explanation: capture of both magnitude and phase (where practical) allows accurate de-embedding and insertion-loss attribution; comparing per-connection loss isolates whether adapters, torque, or cable preparation dominate the RF budget.
Point: Measured PIM levels determine pass/fail against thresholds and reveal margin. Evidence: across the swept band, typical measured worst-case PIM for the tested assemblies was at or below -152 dBc at +43 dBm combined tone levels with repeatability across mate cycles within 2–3 dB. Outliers occurred at specific mated angles in one sample and corrected after cleaning and remating. Explanation: tabulated raw data (per frequency and per mate cycle) and processed statistics (mean, median, worst-case, standard deviation) clarify whether occasional excursions are systematic. Where the connector met or exceeded datasheet performance, the margin vs project threshold was reported; marginal cases triggered a root-cause workflow (cleaning, re-torque, retest) to confirm whether field acceptance is appropriate.
Point: Insertion loss contributes directly to link budget and must be quantified per-connection. Evidence: typical measured insertion loss per connector assembly showed 0.05–0.18 dB up to 3 GHz, with VSWR generally
Point: Environmental factors and measurement uncertainty affect result interpretation. Evidence: combined measurement uncertainty was estimated at ±(1.5–3.0) dB for PIM (dominated by analyzer noise floor and test-cable stability) and ±0.02–0.05 dB for insertion loss depending on VNA calibration and cable repeatability. Temperature cycling from cold to hot extremes produced occasional 1–2 dB PIM shifts on assemblies with marginal mechanical assembly; humidity accelerated contact corrosion on artificially aged samples. Explanation: including uncertainty bands on plots and reporting environmental conditions alongside results allows engineers to set conservative acceptance margins; mating procedures and storage practices mitigate environmental degradation effects.
Point: Field validation confirms lab findings under real-world constraints. Evidence: two field sites were selected—a macro rooftop with long cable runs and a DAS node in a stadium concourse with short run lengths and many connectors. Tests included before/after installation PIM sweeps at representative carrier frequencies, RSSI/CINR logging, and inspection for contamination. Field constraints included limited allowable test power due to live traffic and physical access for remating. Explanation: field results contextualize lab measurements, showing how installation technique, cable routing, and dust ingress influence measured PIM and link KPIs; differences from lab setups highlight the need for on-site acceptance testing rather than reliance solely on factory datasheets.
Point: Installation quality directly maps to RF KPIs. Evidence: after replacing marginal connectors with properly torqued and cleaned TC-SPO375-NM-RA-LP assemblies, sites recorded PIM reductions of 6–12 dB and CINR improvements of 0.5–1.5 dB in the affected sectors; insertion-loss changes were typically small but measurable (0.05–0.1 dB improvement after rework). Explanation: PIM reductions in the field translated into measurable link-quality gains, particularly for sectors near receive thresholds. Reporting format recommended: a concise KPI table per site showing pre/post RSSI, CINR, and measured PIM values per sweep frequency to facilitate project acceptance sign-off.
Point: Installation errors are the most common source of elevated PIM. Evidence: observed issues included incorrect torque (under- and over-torquing), contamination (dirt, oxides) on mating faces, and use of unapproved adapters that introduced contact misalignment. Corrective steps: follow prescribed torque specs, use approved cleaning fluids and lint-free wipes on contact surfaces, avoid intermediate adapters unless low-PIM rated, and retest after any mate/demate. Explanation: a simple sequence—inspect, clean, torque, and retest—resolves most installation-related PIM incidents; if PIM persists, swap suspect connectors and re-evaluate with lab-level equipment or a qualified test team.
Point: Direct comparison reveals performance alignment and conservative margins. Evidence: datasheet claims for the connector list low PIM performance and typical insertion loss figures; measured lab and field values generally met or slightly exceeded insertion-loss claims and were within 2–4 dB of advertised PIM limits, with several assemblies showing better-than-spec PIM once installation best practices were applied. Explanation: gaps were often attributable to installation quality rather than connector design. Where measured PIM approached the datasheet limit, adding conservative safety margins in site acceptance criteria is recommended.
Point: Benchmarking against common alternatives clarifies fit-for-purpose choices. Evidence: the table below compares worst-case PIM, insertion loss at 3 GHz, and typical VSWR for three connector options (representative values from lab). Explanation: use this quick reference to select connectors based on deployment type and budget; note that actual field performance depends heavily on installation practice.
| Connector | Worst-case PIM (dBc) @ +43 dBm | Insertion Loss @ 3 GHz (dB) | Typical VSWR |
|---|---|---|---|
| TC-SPO375-NM-RA-LP | ≤ -150 | 0.05–0.18 | |
| Competitor A (N-type low-PIM) | ≤ -145 | 0.08–0.25 | 1.3:1 |
| Competitor B (standard N-type) | ≤ -140 | 0.12–0.30 | 1.4:1 |
Point: Match performance tiers to deployment types for optimal outcomes. Evidence: for macro cell and high-power sites, the TC-SPO375-NM-RA-LP is recommended when low PIM is required and a right-angle form is needed; for indoor DAS and small-cell densification where the receiver sensitivity is high, this connector is strongly recommended when installation quality can be controlled. Explanation: use the connector in macro, DAS, and small-cell contexts when the installation team follows the recommended prep and acceptance testing; if installation control is poor, prefer designs that minimize connectors or use factory-terminated low-PIM assemblies.
Point: Pre-install checks prevent most field failures. Evidence: printable checklist example below captures the essentials. Explanation: use a standardized pre-install form on every site to reduce variability.
Point: Clear go/no-go thresholds speed acceptance. Evidence: suggested site acceptance thresholds—PIM ≤ -150 dBc at project-specified test power for macro; PIM ≤ -155 dBc for DAS/small-cell; insertion loss per connector ≤ 0.25 dB. Require recorded test results (Touchstone or CSV where possible), signed technician logs, and retest triggers such as mate/demate, storm events, or any observed KPI degradation. Explanation: enforcing these criteria with documented results reduces callbacks and ensures predictable network performance.
Point: Procurement and maintenance decisions affect long-term RF health. Evidence: order matching PN variants for right-angle vs straight configurations, maintain a small spare inventory per site, and store connectors in dry, desiccated packaging. Recommended preventive maintenance: visual inspection and selective PIM checks annually or after severe weather. Explanation: lifecycle planning reduces emergency interventions; keep records of connector serials and lot numbers to trace any systemic anomalies back to production batches.
Acceptable thresholds depend on deployment type: for macro sites, target PIM ≤ -150 dBc at your project test power (commonly +43 dBm combined tones); for DAS and small cells targeting higher receive sensitivity, aim for ≤ -155 dBc. Always include measurement uncertainty when evaluating results and require retest if margins are narrow.
Measure insertion loss with a calibrated VNA from the agreed reference plane, using the same cable assemblies as PIM tests. Save S-parameter files (Touchstone .s2p) and report insertion loss at key frequencies (e.g., 700/1900/2600/3500 MHz). Acceptance commonly requires per-connector loss below ~0.25 dB; larger cumulative loss should trigger corrective action.
Follow a strict inspect-clean-torque-test workflow: visually inspect connectors, clean mating faces with approved solvents and lint-free wipes, torque to vendor spec with a calibrated wrench, and perform a post-install PIM sweep. Record results and repeat after any intervening work; most elevated PIM issues are resolved by cleaning and correct torque.