Milestone-Proposal:Invention and First Demonstration of Radar

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Docket #:2015-01

This Proposal has been approved, and is now a Milestone

To the proposer’s knowledge, is this achievement subject to litigation? No

Is the achievement you are proposing more than 25 years old? Yes

Is the achievement you are proposing within IEEE’s designated fields as defined by IEEE Bylaw I-104.11, namely: Engineering, Computer Sciences and Information Technology, Physical Sciences, Biological and Medical Sciences, Mathematics, Technical Communications, Education, Management, and Law and Policy. Yes

Did the achievement provide a meaningful benefit for humanity? Yes

Was it of at least regional importance? Yes

Has an IEEE Organizational Unit agreed to pay for the milestone plaque(s)? Yes

Has the IEEE Section(s) in which the plaque(s) will be located agreed to arrange the dedication ceremony? Yes

Has the IEEE Section in which the milestone is located agreed to take responsibility for the plaque after it is dedicated? Yes

Has the owner of the site agreed to have it designated as an IEEE Milestone? Yes

Year or range of years in which the achievement occurred:


Title of the proposed milestone:

Demonstration of a Radar Predecessor, 1904

Plaque citation summarizing the achievement and its significance:

On 17 May 1904, near this site, Christian Hülsmeyer demonstrated his Telemobiloskop: a spark gap transmitter, simple parabolic antennas, detector, and an indicator. It was designed to ring a bell when a barge passed the system at a range of several hundred meters. He patented this device in Germany, the United Kingdom, and the U.S.A. This was the world's first operable device to detect radio reflections, a predecessor of radar.

200-250 word abstract describing the significance of the technical achievement being proposed, the person(s) involved, historical context, humanitarian and social impact, as well as any possible controversies the advocate might need to review.

IEEE technical societies and technical councils within whose fields of interest the Milestone proposal resides.

In what IEEE section(s) does it reside?


IEEE Organizational Unit(s) which have agreed to sponsor the Milestone:

IEEE Organizational Unit(s) paying for milestone plaque(s):

Unit: IEEE Germany Section
Senior Officer Name: Prof. Jens Haubrock, Chair

IEEE Organizational Unit(s) arranging the dedication ceremony:

Unit: MTT/AP Joint Chapter (CH08008)
Senior Officer Name: Dr. Peter Knott, Chair

IEEE section(s) monitoring the plaque(s):

IEEE Section: IEEE Germany Section
IEEE Section Chair name: Prof. Ingo Hahn

Milestone proposer(s):

Proposer name: Hugh Griffiths
Proposer email: Proposer's email masked to public

Proposer name: Peter Knott
Proposer email: Proposer's email masked to public

Proposer name: Wolfgang Koch
Proposer email: Proposer's email masked to public

Please note: your email address and contact information will be masked on the website for privacy reasons. Only IEEE History Center Staff will be able to view the email address.

Street address(es) and GPS coordinates in decimal form of the intended milestone plaque site(s):

The western shore end of the Hohenzollernbrücke, Cologne (The original bridge "Feste Brücke" has been replaced by this one in the same location), 50.94100000 N 6.96277778 E

Describe briefly the intended site(s) of the milestone plaque(s). The intended site(s) must have a direct connection with the achievement (e.g. where developed, invented, tested, demonstrated, installed, or operated, etc.). A museum where a device or example of the technology is displayed, or the university where the inventor studied, are not, in themselves, sufficient connection for a milestone plaque.

Please give the address(es) of the plaque site(s) (GPS coordinates if you have them). Also please give the details of the mounting, i.e. on the outside of the building, in the ground floor entrance hall, on a plinth on the grounds, etc. If visitors to the plaque site will need to go through security, or make an appointment, please give the contact information visitors will need.


The site is on the western banks of the Rhine, right next to the Hohenzollern Bridge where the original experiment was conducted.

Are the original buildings extant?

The original demonstration was outdoors

Details of the plaque mounting:

The plaque will be securely mounted on an outdoor wall, protected by a toughened glass window to protect it from the weather and from damage.

How is the site protected/secured, and in what ways is it accessible to the public?

The site is fully accessible to the public

Who is the present owner of the site(s)?

The City of Cologne

What is the historical significance of the work (its technological, scientific, or social importance)? If personal names are included in citation, include justification here. (see section 6 of Milestone Guidelines)

The German engineer and entrepreneur Christian Hülsmeyer first had the idea to build a device for detecting and locating objects by means of reflected electromagnetic waves, after witnessing a collision between two ships on the River Rhine under conditions of poor visibility in which several people were killed. He founded his own company, raised venture capital and developed the technical concept of a radar system. He also patented his invention (which he called a ‘Telemobiloskop’) and first demonstrated it in Cologne, Germany, in 1904. These were the foundations of modern radar systems which, today, contribute to many areas of our life: not only in military, meteorological and air traffic control applications, but also in geoscience, automotive, industrial and even home applications.

What obstacles (technical, political, geographic) needed to be overcome?

At the time of Hülsmeyer's invention, RF technology was still in its infancy, and the available electronic devices were therefore quite primitive. Nevertheless, he was able to build and demonstrate a working prototype equipment. Two pages from Hülsmeyer’s British patent show the basic form of the equipment: it used a spark gap transmitter, simple parabolic antennas, a crude detector and an indicator to show the presence of a target. The title of the patent was: ‘Herzian-wave Projecting and Receiving Apparatus Adapted to Indicate or Give Warning of the Presence of a Metallic Body, such as Ships or Train, in the Line of Projecting of such Waves’.

What features set this work apart from similar achievements?

Specifically, Hülsmeyer and business partner gave a public demonstration of his radar-like apparatus, an account of which appeared in the Kölnische Zeitung newspaper dated 18 May 1904. The site of the demonstration was next to the Hohenzollern Bridge over the River Rhine, and the experiment demonstrated the ringing of a bell when a barge passed in front of the system at a range of several hundred yards. The experiments and the equipment are described in the excerpts from books by Brown, Pritchard and Swords, and the papers by Bauer and Colin. Other scientists and engineers, including Nikola Tesla and Guglielmo Marconi, had suggested that it might be possible to detect objects using reflected electromagnetic waves, but Hülsmeyer’s work was the first practical demonstration and the subject of the first patents. Despite the evident technical success of the demonstration, Hülsmeyer’s invention was not a commercial success. Later in 1904 he demonstrated it in The Netherlands to various hipping lines and navies, but they were not interested, presumably because it was believed that Marconi’s recent invention of radiotelegraphy would be adequate for their needs. Later, in the 1920s and 1930s, work in various countries developed radars that could detect aircraft, and to measure the height of the ionosphere. By that time RF technology – transmitters, antennas, receivers and detectors – had advanced significantly. Some sources – particularly the British scientist Sir Robert Watson-Watt who developed the British Chain Home radar system in the UK in the late 1930s – maintain that Hülsmeyer’s invention could not properly be called a radar because it did not measure range (the term ‘radar’, standing for radio detection and ranging, had first been introduced in the USA on 19 November 1940). This is not strictly true, since a development of Hülsmeyer’s invention, detailed in a subsequent patent granted on 2 April 1906, did indeed measure target range. In addition, we have no difficulty today in speaking of police Doppler radars – which measure target velocity but not range.

Supporting texts and citations to establish the dates, location, and importance of the achievement: Minimum of five (5), but as many as needed to support the milestone, such as patents, contemporary newspaper articles, journal articles, or chapters in scholarly books. 'Scholarly' is defined as peer-reviewed, with references, and published. You must supply the texts or excerpts themselves, not just the references. At least one of the references must be from a scholarly book or journal article. All supporting materials must be in English, or accompanied by an English translation.

Arthur O. Bauer, Christian Hülsmeyer and about the early days of radar inventions - a survey, Diemen, 2005

Supporting materials (supported formats: GIF, JPEG, PNG, PDF, DOC): All supporting materials must be in English, or if not in English, accompanied by an English translation. You must supply the texts or excerpts themselves, not just the references. For documents that are copyright-encumbered, or which you do not have rights to post, email the documents themselves to Please see the Milestone Program Guidelines for more information.

1. Louis Brown: Technical and Military Imperatives: a Radar History of World War II, Taylor & Francis, 1999.

2. David Pritchard: The Radar War: Germany’s Pioneering Achievement 1904-1945, Harper Collins, 1989.

3. Sean Swords, Technical History of the Beginnings of Radar, Peter Peregrinus, 1986.

4. Arthur O. Bauer: Christian Hülsmeyer and about the early days of radar inventions - a survey, Diemen, 2005 [a detailed description of Hülsmeyer’s work and patents written by a Dutch historian and made available on his website ]

5. A Special Session at the SEE/IEEE International Radar Conference in Toulouse, France in 2004 to mark the centenary of Hülsmeyer’s invention. Several of the papers are in French, but two in English are:

Arthur O. Bauer: ‘Hülsmeyer’s early radar commitments’

Jean-Marie Colin: ‘Radar innovation and proofs from C.Hülsmeyer’

Please email a jpeg or PDF a letter in English, or with English translation, from the site owner(s) giving permission to place IEEE milestone plaque on the property, and a letter (or forwarded email) from the appropriate Section Chair supporting the Milestone application to with the subject line "Attention: Milestone Administrator." Note that there are multiple texts of the letter depending on whether an IEEE organizational unit other than the section will be paying for the plaque(s).

Please recommend reviewers by emailing their names and email addresses to Please include the docket number and brief title of your proposal in the subject line of all emails.