Wullenweber Direction Finder
By G. W. Swenson, Jr.
1 September, 1994
[Editor's note: Since the time of Professor Swenson's writing, this site has been dismantled.]
View the large-aperture radio direction finding system known as a Wullenweber array at the Bondville Road Field Stadium, October 1960. Operating at a frequency range from 4 to 16 MHz, the array uses 120 antennas and is 1000 ft in diameter.
The "ring of poles" south of Bondville is properly known as the "wide aperture direction finder" or "Wullenweber direction finder." What you see is the decrepit remnant of an elaborate radio antenna system that was developed for the U.S. Navy in the 1950s and 60s by the Electrical Engineering Department of the University of Illinois under the direction of Professor Edgar Hayden. He was succeeded by Professor Albert Bailey (deceased) and then by Professor Edward Ernst (now at the University of South Carolina).The local individual most knowledgeable about the project is Walter Wood (retired) of Savoy.*
The Wullenweber consisted of a ring of 120 vertical monopole antennas, effective in the frequency band of 2-20 MHz. The tall wooden poles you see supported a circular screen of vertical wires within the ring of antennas. In operation, 40 contiguous dipoles at a time were connected to a radio receiver at the center of the ring, thus forming a highly directive receiving antenna array. By means of some very elaborate electronics which connected successive antennas sequentially around the ring, the receiving "beam" was swept around all points of the compass. By monitoring the output of the radio receiver as the array was scanned, the direction of arrival of a particular radio signal could be determined.
The Navy eventually built a worldwide network of such Wullenweber direction finders. By correlating the measurements from two or more of them, the location of a particular radio transmitter (and thus of the ship or installation containing it) could be determined.
Following the completion of the University's development work, the Bondville installation was abandoned in approximately 1980. The site is now used for other research purposes by various university and government organizations.
* Note: Walter Wood died in March 2000.