50th Anniversary of the First FM Master Antenna Commemorated at 139th

In today’s radio broadcasting world, it is not uncommon for multiple FM stations to share an antenna system. This arrangement, called a multiplexed or master FM antenna system, provides a more economical way to build FM facilities and is especially popular for stations which have common ownership in the same radio market.

The first-ever master antenna system was built on top of the Empire State Building (ESB) in mid-town Manhattan, New York City, in 1965, and yesterday the ESB and the Audio Engineering Society (AES) commemorated the 50th anniversary of this engineering achievement with a special event in conjunction with the 139th AES Convention held at the Jacob Javits Center in New York City.

Andrew Alford, an American electrical engineer and founder of the Alford Manufacturing Company, designed and built this first-ever master FM antenna system. The antenna itself consists of 32 elements arranged in two rings above and below the observation gallery on the 102nd floor of the ESB. Each ring contains 16 antenna elements which are equally spaced around the building and are shown in the inset in the first photo below, with individual antenna elements marked by the red arrows (the windows of the 102nd floor observation gallery are visible between the upper and lower antenna rings).

This second photo, taken from the ESB’s 102nd floor observation gallery, shows an individual antenna element with the New York cityscape (and the East River) below.

Alford Antenna

In the 1990s, a new master antenna was built on the ESB by Electronics Research, Inc. (ERI) and today the original Alford antenna is used in a backup capacity only. Sixteen FM stations broadcast on the ERI master antenna and their signals are combined in a combiner room on the 85th floor. NAB Senior Director Advanced Engineering David Layer (shown in photo below at left) was given a tour of the FM Master Antenna combiner at the Empire State Building by ERI President (and new master antenna builder) Tom Silliman (in photo at right). David and Tom are surrounded by the multiplex filters used to combine the individual FM signals. A “mini master” FM antenna is also in use on the ESB for three additional FM signals, bringing the total number of FM stations broadcasting from the ESB to 19 (listed in the table below).

Combiner room
As part of the special celebration at the AES convention, WCBS-FM (101.1 MHz) aired the Steely Dan song “FM” at 7PM after a special on-air announcement about “WCBS-FM and the Audio Engineering Society celebrating the 50th anniversary of the master FM antenna at the top of the Empire State Building,” asking listeners to “…look up at the Empire State building and crank up your radio and enjoy a light show set to the music of Steely Dan on CBS-FM.” A specially-invited group of AES attendees and radio broadcasting enthusiasts viewed the light show from the Monarch Rooftop Lounge at 71 W 35th in mid-town Manhattan, just a block from the ESB (see video below).