Diplexer vs Duplexer
A diplexer separates two different frequency bands on a common port — directing Band 1 to Port 2 and Band 2 to Port 3, while maintaining high isolation between Port 2 and Port 3. Unlike a duplexer (which separates TX/RX of the same band), a diplexer handles two distinct bands sharing one antenna or interconnect.
Common Diplexer Applications
| Application | Band 1 | Band 2 |
|---|---|---|
| WiFi + Bluetooth combo | 2.4 GHz (BT+WiFi) | 5 GHz (WiFi) |
| 5G NR + LTE combo | Sub-1 GHz LTE | Mid-band 5G NR |
| GPS + cellular | 1575 MHz (GPS L1) | 1700–2700 MHz cellular |
| Cable TV diplexer | 5–85 MHz (upstream) | 88–860 MHz (downstream) |
Key Diplexer S-Parameter Specifications
3-port diplexer: Port 1 = Common (antenna), Port 2 = Band 1, Port 3 = Band 2 S21: Common → Band 1 insertion loss (Band 1 passband) S31: Common → Band 2 insertion loss (Band 2 passband) S11: Common port return loss (in both Band 1 and Band 2) S22: Band 1 port return loss (in Band 1) S33: Band 2 port return loss (in Band 2) S23: Band 1 → Band 2 isolation (critical!)
Analysis Steps in RF View
- Load diplexer .s3p file → extract port pairs:
- Common↔Band1: ports 1,2 → save as diplexer_band1.s2p
- Common↔Band2: ports 1,3 → save as diplexer_band2.s2p
- Band1↔Band2 isolation: ports 2,3 → save as diplexer_isolation.s2p
- Load diplexer_band1.s2p → S21: verify Band 1 IL and passband
- Load diplexer_band2.s2p → S21: verify Band 2 IL and passband
- Load diplexer_isolation.s2p → S21: verify Port 2 to Port 3 isolation
- Both band files → S11 (common port): verify match in both bands
RF View Diplexer Analysis: RF View reads .s3p diplexer files and supports port-pair extraction. Load all extracted .s2p files simultaneously for complete diplexer characterization in one session. Free on Android.