Phillystran Aramid Fiber Guy Lines meet evolving Sutro Tower needs


Dominating the San Francisco skyline, the “Bay Area’s Essential Connection”, the Sutro Tower relies on Phillystran HPTG-I tower guys to support the three stacks atop the tower with the many TV and radio antennas. The Sutro Tower is a 977 ft (298 m) three-legged tower located 834ft above sea level.

Before the construction of the Sutro Tower in 1973, television reception in San Francisco was patchy due to the city’s many hills blocking the line-of-sight television signal. The height of the tower solved the problem, allowing the Bay Area’s 11 television station antennae, FM Radio station antennae and numerous antennae for essential communications services to be placed in one location. The Sutro tower’s three stacks were initially guyed with fiberglass rods. However, the rods had a limited life expectancy as well as diameter/size restrictions. In 1990, they were replaced with Phillystran High Performance Tower Guys (HPTG-I).

The Phillystran HTPG-I aramid fiber guying system is ideal for large antennae. It eliminates problems associated with EHS and BS steel guy cables such as: ElectroMagnetic Interference (EMI), Radio Frequency Interference (RFI), Signal Suppression, Array Directional Irregularities and white noise.

HPTG-I aramid fiber guy lines are approx one fifth the weight of comparable steel wire ropes with the same strength helping Sutro Tower Inc meet weight reduction/wind load goals.

It also has the benefit of scalability. In 1990, HPTG 27000I cable guys were used with a breaking strength of 27,000 lbs.  In 2009, all three Sutro Tower stacks were re-guyed with a combination of Phillystran HPTG 85000I and HPTG 130000I guys following a structural analysis of the Tower, resulting in increases in the stack guy size requirements.  Again in 2019 the south stack guys were all replaced with HPTG 130000I as a result of the recent FCC bandwidth re-bundle requirements.

Phillystran HTPG-I – the complete antennae guying system

Phillystran’s HPTG-I aramid fiber guy lines are one component of the HPTG-I Guying System. The complete guying system includes the HPTG-I guy lines with either the Corona, Big Grip Dead-Ends or standard end wire terminations, together with vibration dampers and steel tails, as required.