# A Switched-Line True Time Delay Unit for Wideband Phased Arrays Using Packaged RF MEMS Switches

## TL;DR

This paper introduces a new RF MEMS-based time delay unit for wideband phased arrays, using off-the-shelf components and standard PCB processes.

## Contribution

A practical, scalable RF MEMS-based TDU using commercial components and standard PCB fabrication is demonstrated for the first time.

## Key findings

- The TDU operates from 0.4 to 6 GHz with a delay range of 0–413 ps and an average insertion loss of 1.5 dB.
- The design achieves a delay error below 18.4 ps and a figure of merit of 152.8 ps/dB.
- A refined switch/termination model aligns simulations with measurements, validating the design.

## Abstract

The growing demand for wideband electronically scanned arrays (ESAs) in next-generation radar, satellite, and 5G/6G systems has renewed interest in true time delay units (TDUs) to overcome the limitations of phase-based beamforming. In parallel, recent advances in the commercial availability and reliability of packaged RF MEMS switches have enabled practical hardware implementations once considered infeasible. This paper presents the design, fabrication, and experimental validation of a broadband, 4-bit switched-line TDU using only off-the-shelf components and standard PCB processes. The unit operates from 0.4 to 6 GHz, with a total delay range of 0–413 ps, achieving an average insertion loss of 1.5 dB and delay error below 18.4 ps, resulting in a figure of merit (FOM) of 152.8 ps/dB. Measured results are reported alongside a refined switch/termination model that aligns simulations with measurements. This is among the first reported demonstrations of a complete RF MEMS-based TDU implemented entirely with commercially available components in a standard PCB-integrated implementation. These results demonstrate a practical pathway toward scalable MEMS-based TDUs for deployment in advanced beamforming systems.