PE51113-4 Measured Specs: Frequency, Gain & VSWR Deep Dive
The article opens with measured S-parameter and far-field datasets produced on a controlled testbench: calibrated S11/return-loss sweeps, gain-versus-frequency points and VSWR curves drive the interpretation of on-air behavior. This write-up uses those measured outputs to explain what the numbers mean for designers evaluating the PE51113-4, framing frequency coverage, gain trends and VSWR interaction into concrete design decisions.
Background Why Measured Specs Matter & Test Setup for the PE51113-4
Test equipment, reference planes & standards to cite
Point: Reliable interpretation requires a repeatable, documented testbench.
Evidence: Use a vector network analyzer (VNA) with full two-port port-calibration, coaxial-to-fixture de-embedding and a verified far-field range or anechoic chamber for pattern work.
Explanation: Typical setup includes a port-calibrated VNA, fixture de-embedding to the antenna feed, anechoic chamber with reference antenna for gain comparison, SMA connector with torque spec, and a PCB or magnetic mount specified for the part.
Key metrics defined: frequency, gain, VSWR
Point: Metrics must be defined with equations and tolerance bands.
Evidence: S11 in dB is 20·log10(|Γ|); VSWR = (1+|Γ|)/(1-|Γ|). Realized gain (dBi) equals measured far-field level minus reference antenna correction and cable losses.
Explanation: Report bandwidths using -3 dB, -6 dB and -10 dB points, state measurement uncertainty (typically ±0.5–1.5 dB for gain, ±0.2–0.5 dB for S11).
Data Analysis Measured Frequency Response & Bandwidths
Reading S11 plots: resonant peaks, nulls and usable bandwidth
Point: The S11 trace reveals resonances, nulls and usable bands. Evidence: Annotate the |S11| (dB) plot with resonant frequencies and mark -6 dB and -10 dB bandwidths.
Explanation: Resonant dips align with peak realized gain; asymmetries or spurious resonances indicate possible coupling or mounting effects and may require filtering.
Long-tail frequency observations & implications
Point: Response outside main bands matters for filters and duplexing. Evidence: Long-tail sidelobes or shallow roll-off in the S11 curve indicate energy at adjacent frequencies. Explanation: Translate those items into actions: specify input filters where required, plan duplex spacing conservatively.
Data Analysis Measured Gain & Radiation Pattern Deep-Dive
Gain vs. Frequency
Point: Peak gain sets link-budget expectations. Evidence: Present peak dBi versus frequency points. Explanation: Expect realized on-air gain to be lower than an idealized nominal—plan for a conservative delta of 0.5–2 dB in real deployments.
Radiation Patterns
Point: Pattern shape determines coverage. Evidence: Annotated pattern cuts (E-plane/H-plane) labeling main lobe and beamwidth. Explanation: Narrower main lobes increase directional range but reduce coverage angle; higher sidelobes can create unintended interference.
Method Guide VSWR, Impedance Behavior & Matching Strategies
Interpreting VSWR plots and acceptable thresholds
Point: VSWR vs. frequency quantifies reflected power. Evidence: Plot VSWR with thresholds (1.5:1, 2:1) and correlate with return-loss points. Explanation: VSWR ≤ 2:1 is commonly acceptable; larger values indicate mismatch—expect increased insertion loss.
Practical Matching Checklist
- Check connector torque
- Shorten problematic coax
- Add L/C matching networks
- Tune ground plane
- Use absorbers
Actionable Field Use Cases, Troubleshooting & Selection Guidance
Application Scenarios
- Mobile LTE: Min gain ~2–4 dBi, VSWR ≤ 2:1.
- IoT Gateway: Broadband presence, stable pattern.
- Private Networks: Consistent realized gain, low sidelobes.
Troubleshooting Sequence
- Verify connectors and torque.
- Re-run S11 sweep with VNA.
- Compare far-field pattern frequencies.
- Swap mounting location.
