CHICAGO—For more than four decades, Installation Services has been synonymous with RF atop Chicago’s Willis Tower. From early collaboration with the late and esteemed broadcast engineer Jeremy Ruck to coordinating antenna systems and transmission lines to helicopter lifts and structural upgrades, our team has worked on nearly every major broadcast installation on the building since the 1980s.
Most recently, we completed one of the most complex projects in the tower’s history: replacing an aging Dielectric triple-stack antenna system with two new UHF systems serving WLS-TV, WFLD-TV and WMAQ-TV.
The Importance of Advanced Planning
The original triple-stack system dated back to the industry’s digital transition in the late 1990s. It served Chicago viewers well for more than two decades, but evolving operational requirements and long-term infrastructure planning made it time for an upgrade. The new configuration includes a Dielectric TFU double-stacked slot antenna system for WLS-TV and WFLD-TV, along with a separate single-slot antenna UHF installation for WMAQ-TV. Both systems feature vertically polarized design elements to improve building penetration.
Projects of this scale begin long before anything leaves the ground. Planning alone took roughly one year and involved structural analysis, engineering reviews, fabrication work, Federal Aviation Administration and Federal Communications Commission coordination, city approvals and extensive lift planning. On a structure as prominent as Willis Tower, every component must meet rigorous engineering and Chicago building code requirements. Multiple engineering teams and third-party reviewers evaluated every detail to ensure the systems would meet performance expectations for decades to come.
Before installation could begin, we first had to remove the existing 18,500-pound triple-stack antenna system. Using Helicopter Express’ heavy-lift aircraft, we dismantled the legacy system into sections and safely lowered it from the tower. Preparation work included replacing aging hardware with new bolts ahead of the lift to ensure smooth field operations during the critical removal window.
The replacement systems required substantial site preparation as well. We removed and replaced the original top plate assembly atop the tower with a newly engineered structure designed to current standards. That alone required a separate helicopter lift and additional reinforcement work beneath the mounting structure to properly tie everything into the tower.
Once the site was prepared, the real installation work began. The WMAQ-TV installation included a massive, fabricated transition section—what we refer to as the “wedding cake”—which serves as the primary support structure for the antenna above it. We also installed rigid transmission line systems to extend multiple floors down into the transmission facilities below.
The Big Lift
Coordinating the helicopter lifts is one of the most demanding aspects of projects like this. We shut down more than a dozen city streets, halted pedestrian traffic and coordinated with dozens of workers, engineers and public safety personnel. During lift operations, virtually every major TV and FM station on the building had to temporarily power down. It’s an enormous logistical undertaking that started before sunrise and requires precision from everyone involved.
Once the antennas were installed, the work shifted toward final optimization. Our crews spent weeks torquing hardware, verifying structural integrity and preparing the RF systems for operation. Third-party inspectors reviewed the completed work, after which transmission lines were connected and tuned. Dielectric engineers then performed system sweeps and final RF optimization to ensure peak performance across the entire transmission system.
These are extremely high-power broadcast facilities serving one of the nation’s largest television markets, so every detail matters. Seeing the new Dielectric systems successfully installed and operating atop Willis Tower is something that brings tremendous pride to our entire team. Projects like this remind you how much planning, engineering and teamwork go into keeping over-the-air television operating reliably for millions of viewers every day.
For more information, visit Dielectric’s website.
