When designing a high-frequency system—whether for 5G communication, radar, Wi-Fi 6E, or RF lab testing—your choice of coaxial cable plays a critical role in performance. But a common question arises:
“How high can a coaxial cable go in frequency before it fails to perform well?”
In this guide, we’ll explain what “maximum frequency” really means in coaxial cable specifications, how different types compare, and how to choose the right cable for your GHz-level applications.
Why Max Frequency Matters in RF Cable Selection
Coaxial cables are not all the same. Each model has a maximum frequency rating, which defines the highest frequency it can carry without excessive signal loss or distortion. If you exceed that limit, you risk:
- Severe signal attenuation
- Impedance mismatch
- Poor VSWR and return loss
- EMI leakage or interference
This is especially critical in systems operating above 1 GHz, where minor losses become exponential.
What Does “Max Frequency” Mean?
The “maximum frequency” of a coaxial cable refers to the highest frequency at which the cable can carry a signal while still maintaining acceptable performance, usually defined by:
- Insertion Loss (attenuation per meter or foot)
- VSWR (voltage standing wave ratio)
- Return Loss
- Shielding effectiveness
Note: Manufacturers often define max frequency as the point where VSWR > 1.5 or insertion loss exceeds 6 dB/100ft.
Factors That Affect Max Frequency
| Factor | Impact on High-Frequency Capability |
|---|---|
| Dielectric Material | PTFE and PE have better GHz performance than PVC |
| Shielding | Quad shielded or foil + braid designs reduce leakage |
| Diameter & Skin Effect | Smaller diameters have more skin loss at high GHz |
| Connector Quality | SMA, N-Type are better than UHF at GHz-level |
| Cable Length | Loss scales with length—shorter cables perform better at high f |
Frequency Ratings of Common Coaxial Cables
| Cable Type | Max Recommended Frequency | Impedance | Use Case |
|---|---|---|---|
| RG-58 | Up to 1 GHz | 50Ω | Short RF runs, VHF/UHF |
| RG-213 | Up to 1.5 GHz | 50Ω | HF/VHF base stations |
| RG-6 (75Ω) | Up to 2 GHz | 75Ω | Satellite TV, DVB-T |
| LMR-195 | Up to 6 GHz | 50Ω | Wi-Fi, GPS, telemetry |
| LMR-400 | Up to 11 GHz | 50Ω | 5G, microwave, test systems |
| LMR-600 | Up to 15 GHz | 50Ω | Long-range 5G, radar, CPE |
| Semi-Rigid | Up to 18 GHz+ | 50Ω | Lab testing, aerospace, defense |
📎 Reference: Times Microwave Coax Data
How to Know If Your Cable Is Suitable
Ask Yourself:
-
What is your system’s operating frequency?
→ Is it under 1 GHz (e.g., HF/VHF) or above 6 GHz (e.g., 5G, Wi-Fi 6E)? -
How long is your cable run?
→ Longer cables = more attenuation. -
What connector types are used?
→ SMA and N-Type are recommended for >1 GHz. -
Do you require lab-grade accuracy?
→ Use semi-rigid or ultra-low-loss options. -
Will the cable be installed outdoors?
→ Use PE jacketed, UV-resistant cables like LMR-400.
Practical Examples
Case 1: Wi-Fi 6E Router (6 GHz) to External Antenna
- Don’t use RG-58 or RG-6 (loss too high)
- Recommended: LMR-400 with RP-SMA or N-Type
- Attenuation at 6 GHz for LMR-400: ~6.6 dB/100 ft
Case 2: SDR System Testing 10 GHz Band
- Use semi-rigid coax (e.g., RG-405) with SMA
- Keep cable under 1 meter
- Expect loss ~3 dB/m at 10 GHz
Case 3: 5G Outdoor CPE to Antenna (7 GHz)
- Use LMR-600 with N-Type waterproof connectors
- Heat-shrink sealed, UV-stable jacket
- Ask us for preterminated assemblies
Matching Frequency to Coax: Quick Guide
| Frequency Band | Coax Recommendation | Notes |
|---|---|---|
| HF (3–30 MHz) | RG-213, RG-8X | Large diameter, low-loss |
| VHF/UHF (30–500 MHz) | RG-213, LMR-195 | Good balance of cost and loss |
| 2.4 GHz / 5 GHz | LMR-200, LMR-400 | Avoid RG cables here |
| 6–10 GHz (Wi-Fi 6E, 5G) | LMR-400+, Semi-Rigid | Only high-grade cables |
| 10–18 GHz (Lab, Radar) | RG-405, RG-402 | Semi-rigid coax + precision SMA |
Are Your Connectors Also Limiting Frequency?
Even the best cable won’t help if your connectors are mismatched.
| Connector Type | Max Frequency | Comments |
|---|---|---|
| PL-259 (UHF) | ~300 MHz | Not suitable above 500 MHz |
| BNC | ~4 GHz | Widely used, decent GHz range |
| SMA | ~18 GHz | Gold standard for lab setups |
| N-Type | ~11 GHz | Preferred for 5G, outdoor RF |
Common Mistakes to Avoid
- ❌ Using RG-58 for anything above 2 GHz
- ❌ Mixing 50Ω and 75Ω cables
- ❌ Using UHF connectors on 5G systems
- ❌ Ignoring attenuation charts in datasheets
Bafitop’s High-Frequency Cable Solutions
At Bafitop, we offer a full range of coaxial cables tested and rated for high-frequency RF applications:
Our High-Frequency Cable Lines:
- LMR-195 / LMR-400 / LMR-600 equivalents
- Semi-rigid coax (e.g., RG-405, RG-402)
- Custom-length cable assemblies with SMA / N-Type connectors
- Low VSWR, low-loss, lab-tested specs
- Outdoor-rated jackets, double-shielded options
Whether you’re building a test lab or outdoor microwave link, we’ve got your signal covered.
Get Technical Guidance or a Free Sample Today
Need help choosing the right coax for your GHz-range system?
We provide:
- Technical consultation
- Pre-sales support
- Custom samples
- Worldwide shipping
📧 Email: sales@bafitop.com
📞 Phone: +86-15817341810
Request a Quote or Sample →
FAQ: Maximum Frequency in Coaxial Cables
Q1: Is it dangerous to use coax above its rated frequency?
Not dangerous, but it will degrade signal integrity. Expect increased insertion loss and poor return loss.
Q2: Can I extend a 6 GHz link with RG-58?
No. RG-58 has ~25 dB loss per 100 ft at 6 GHz—unusable for quality transmission.
Q3: What’s the best connector for 10 GHz systems?
SMA is preferred. For critical systems, use precision SMA with semi-rigid coax.
Q4: Does cable bending affect high-frequency performance?
Yes. Excessive bending can change impedance and introduce reflection at GHz speeds.
Q5: Can I use adapters to convert UHF to SMA or N-Type?
You can, but every adapter introduces reflection and minor loss—avoid if possible at >3 GHz.
