News - Why Signal Gets Weaker After Adding a Filter – Engineering Insights from Concept Microwave

Why Signal Gets Weaker After Adding a Filter – Engineering Insights from Concept Microwave

March 2026 – Concept Microwave

We often hear customers ask: “We added a filter to remove interference, but the signal became weaker. Is the filter bad?”

In most cases, the filter is not the problem. The real issues lie in system design or integration. Here are six common reasons – and how we help solve them.

1. Insertion loss

Every filter has loss (typically . When added to long cables and connectors, the total loss can exceed your link budget.
✅ Our datasheets give clear insertion loss values for accurate planning.

2. Frequency mismatch

If the filter’s passband does not fully cover your operating frequencies, edge signals are attenuated.
✅ *We offer custom-tuned filters and diplexers

3. Accumulated chain loss

A filter is often the “last straw” after feeders, splitters, and jumpers have already consumed power.
✅ Our compact microstrip diplexers minimise added loss.

4. Impedance mismatch (high VSWR)

Poor 50Ω matching causes signal reflection, unstable coverage, and wasted power.
✅ All our products are tested for VSWR ≤2.0 with SMA-female connectors.

5. Unintentional filtering of wanted signals

In dense bands (DAS, 5G+satellite), an overly narrow filter can reject desired signals.
✅ Our wideband diplexers and high-rejection notch filters (≥70 dB) use guard bands to separate, not degrade.

6. Forgetting the uplink

Mobile phones have much lower transmit power than base stations. Filter loss hurts uplink more – causing slow uploads and battery drain.
✅ We always help customers check uplink budget.