698–3700 MHz, 500 W, Hohlraum-Leistungsteiler: Hochleistungs-Signalverteilung für 5G-Basisstationen

For macro base stations and large DAS systems that need to split 500W signals across 698-3700MHz, MS TELERF’s cavity splitter outperforms microstrip designs. It uses an air-dielectric cavity structure with total insertion loss ≤5.2dB (including 3.0dB theoretical split loss), PIM ≤-150dBc at 2×43dBm, and 7/16 DIN connectors. Made in an ISO-certified Singapore factory, this splitter has been deployed in projects like China Tower’s Ningbo rail transit lines, with thousands of units purchased in single orders.

When RRU output hits 500W in macro base stations and large DAS deployments, the Leistungsteiler choice directly affects coverage quality and long-term reliability. Microstrip Wilkinson splitters struggle above 200W with heat, PIM degradation, and rising insertion loss. Cavity designs solve these problems with no dielectric loss, no heating resistor, and all-metal heat dissipation. This article covers the key specs, design advantages, and deployment practices for this product.

1. Executive Summary

• What it is: MS TELERF 698-3700MHz 500W splitter ist eine 2-way, 7/16 DIN female, cavity-type broadband power divider. Designed for high-capacity macro base stations and large indoor/outdoor DAS, it covers all Sub-6GHz bands from 700MHz LTE to 3.7GHz (including 5G n78).
• How it works: Uses a cavity coaxial structure with air as the transmission medium. Power is split through precision machining. Unlike microstrip Wilkinson designs, cavity splitters have no isolation resistor — no resistive heating, no nonlinear PIM source. No dielectric substrate means no dielectric loss or material nonlinearity. This keeps PIM ≤-150dBc even at 500W.
• Why it matters: Macro RRUs output hundreds of watts. Large venues and subway tunnels need high power to drive remote antennas. Microstrip splitters above 200W run into heat, loss, and PIM problems. Cavity structure is the only choice at 500W — it handles both thermal management and signal purity in high-power multi-carrier environments.

2. Detailed Overview

2.1 Key Electrical Specifications

2.2 How It Works: Cavity vs. Microstrip Wilkinson

Microstrip Wilkinson splitters rely on PCB microstrip lines and isolation resistors. At 500W, the resistor generates significant heat, dielectric loss increases, and performance drifts. Cavity splitters use an air dielectric + metal conductor structure:

• No dielectric loss: Air has tanδ≈0, far better than PCB substrate (tanδ≈0.002-0.005) — lower insertion loss
• No heating resistor: No isolation resistor means no heat source. Power handling is not limited by resistor thermal capacity
• All-metal construction: Aluminum cavity is both electromagnetic shield and heat sink

Why 7/16 DIN: SMA and N-type have small contact areas. At 500W, contact resistance causes noticeable temperature rise and long-term PIM drift. 7/16 DIN’s large flange gives more contact area and higher coupling torque, ensuring long-term electrical stability. It is the standard interface on operator-grade macro base stations.

2.3 Key Advantages

1. 500W CW power handling: Aluminum cavity dissipates heat effectively. China Tower’s Ningbo rail transit project purchased thousands of units from this same series for subway tunnels and large venues — proven reliability in real engineering.
2. Full 5G Sub-6GHz coverage: 698-3700MHz covers all mainstream bands from LTE low-band (Band 12/13/14/17) to 5G n78 (3.3-3.8GHz). One device supports 4G/5G co-location und multi-operator band sharing — fewer SKUs, lower inventory cost.
3. Operator-grade PIM: ≤-150dBc (≤-155dBc on some models) ensures that at 3.5GHz high power, intermodulation products do not fall into receive bands and cause desensitization. Critical for 256-QAM and 1024-QAM data rates.
4. Singapore ISO factory quality: Designed, manufactured, and tested in MS TELERF’s ISO 9001-certified Singapore facility. Every unit undergoes 100% VSWR, insertion loss, and PIM full-parameter testing before shipment.

3. Comparison: Cavity Splitter vs. Microstrip Wilkinson Splitter

4. Deployment Steps

Step 1: Check system power and link budget

• Total loss: 2-way splitter ≤5.2dB (3.0dB theoretical + ≤2.2dB excess). At 500W input, each output delivers about 500W/2 × 10^(-0.52) ≈ 150W
• Ensure input power does not exceed 500W average rating. Check peak power (e.g., TD-LTE burst characteristics)
• Reserve ≥0.5dB loss margin for connectors and cable losses

Step 2: Check environmental conditions

• Operating temperature: -40 °C bis +55 °C
• Relative humidity: 5%-95%, supports outdoor and tunnel high-humidity environments
• If higher ingress protection is needed, check IP65 compliance

Step 3: Install connectors correctly

• Use 7/16 DIN male cables. Tighten to standard torque: 25-30N·m
• Check pin and socket cleanliness. Dust and oxidation add PIM
• Use a Drehmomentschlüssel — under-torque or over-torque both cause contact nonlinearity

Step 4: System integration

• Connect input port to RRU or high-power source
• Connect 2 outputs to antennas or downstream distribution
• For outdoor tower-top installs, mount the cavity vertically for natural convection cooling

Step 5: Performance verification

• Use VNA across 698-3700MHz to verify VSWR ≤1.30
• Use PIM tester at 2×43dBm to verify PIM ≤-150dBc
• Record baseline data for future maintenance reference

5. Common Mistakes

Mistake #1: Using a microstrip splitter for high-power applications

Some engineers use a 200W-rated microstrip Wilkinson splitter in 500W macro site scenarios to save cost or use existing stock. The isolation resistor heats up significantly above 200W, causing drift, PIM degradation, or even burnout. Even at “only” 200W input, high ambient temperature or degraded VSWR can push reflected power past the rating. 500W requires a cavity splitter.

Mistake #2: Ignoring 7/16 DIN torque specs

7/16 DIN connectors require 25-30N·m torque for low contact resistance and PIM stability. Using an ordinary wrench often results in under-torque or over-torque — contact nonlinearity or damaged threads. Correct practice: use a Drehmomentschlüssel, follow the spec, and clean the interface before connecting.

6. FAQ

1. Why does a 500W splitter use cavity structure instead of microstrip?

Cavity is the only choice at 500W. Microstrip Wilkinson splitters have an isolation resistor and PCB substrate. At high power, the resistor heats up, dielectric loss increases, and PIM degrades. Cavity splitters use air dielectric and all-metal construction — no heating resistor, no dielectric loss. The aluminum cavity acts as a heat sink, supporting 500W CW transmission. China Tower’s tender documents explicitly require cavity structure for 500W splitters.

2. What is the PIM spec and test condition?

Typical PIM is ≤-150dBc to -155dBc, tested at 2×43dBm (20W per carrier) CW. This is the industry-standard base station test condition, simulating actual macro site transmit power. High-requirement models can be customized to -160dBc.

3. Why 7/16 DIN instead of N-type or SMA?

7/16 DIN is designed for high-power applications (hundreds of watts) with lower contact resistance, higher coupling torque, and better PIM stability. N-type temperature rise from contact resistance is more noticeable at 500W. SMA is not suitable for this power class at all. 7/16 DIN has become the standard interface for macro sites and large DAS projects.

4. How is heat dissipated across 698-3700MHz at 500W?

The splitter uses a high-grade aluminum cavity — the entire metal housing acts as a heat sink. Inside the cavity, air dielectric has no extra heat source (no isolation resistor). Heat comes mainly from conductor loss (about 0.5-1% of input power). At 500W input, about 2.5-5W dissipates through natural convection from the aluminum cavity. Performance stays stable across -40℃ to +55℃.

5. Has this product been used in real projects?

Yes. China Tower purchased thousands of units from this 500W cavity splitter series (including 2-way, 3-way, and 4-way models) for Ningbo Rail Transit Lines 7 and 8, covering 5G/4G signal distribution in subway tunnels. Single-order quantities reached thousands — proof of operator-level engineering validation.