Couplers — Lesson 3

This lesson covers the 4-port devices known as couplers. It delves into the properties of these devices, explaining how they can be matched, reciprocal, and lossless. The lesson further explores the different types of couplers, their representation, and their functioning. It provides a comprehensive understanding of the signal flow within these devices, the difference between coupled and through ports, and the concept of constructive and destructive interference. The lesson also discusses the hybrid coupler and the division of power within it. It concludes with an explanation of the S-parameter matrix for a 3 dB hybrid.

Video Highlights

00:15 - Introduction
01:22 - Structure and function of couplers
06:14 - Two types of couplers based on the property
11:45 - Branch line hybrid coupler.
21:20 - Cascade parameters or ABCD matrices
26:29 - S parameter matrix for a 3 dB branch line hybrid

Key Takeaways

- 4-port devices, known as couplers, can be matched, reciprocal, and lossless.
- Couplers are represented by a specific symbol and have an input port, a coupled port, a through port, and an isolated port.
- The signal within a coupler travels to the coupled port and the through port, with no part of the input signal reaching the isolated port.
- Hybrid couplers divide power equally between the coupled and through ports.
- The S-parameter matrix for a 3 dB hybrid coupler shows a 90-degree phase shift between outputs.