CENAP Infoline - no 080

Magazine Overview

Title: cenap-infoline
Issue: nr. 80
Date: 3. November 1998
Publisher: cenap-infoline
Country: Germany
Language: German

This issue of cenap-infoline, a supplementary report to CR-252 S.50/53, focuses on "Radar Anomalies." It explores how 60 years of radar technology development have led to the observation of new, often puzzling phenomena on radar screens. The increasing capabilities of radar for target detection and location have also amplified the possibilities for phenomena described as "unexplained targets," which have sometimes caused significant attention and confusion.

The report aims to present typical "cases" of these anomalies, discuss their potential causes and contributing conditions, and highlight the complexity of electromagnetic wave propagation.

Radar Principles and Anomalies

The article explains that "radar beams," primarily electromagnetic waves in the centimeter, decimeter, and meter ranges, behave similarly to light waves but are invisible to humans. Specialized sensors are needed to detect the reflected or scattered waves, which are then processed and displayed visually or digitally.

The principles of radar location generally assume straight-line wave propagation in a homogeneous medium. However, the atmosphere is not uniform, and wave behavior can be affected by diffraction, leading to deflection, often towards the Earth's surface, or away from it under abnormal meteorological conditions.

Early radar equipment was simpler, consisting of a transmitter, receiver, and antennas. Target echoes were detected using headphones or oscilloscopes. With advancements aiming to increase range and detect smaller targets, radar systems became more complex, with increased transmission power (up to megawatts in modern centimeter-wave radars) and sophisticated signal structures like impulses with internal frequency modulation.

Causes of Phantom Targets

Phantom targets, or "false targets," can arise from the medium through which electromagnetic waves propagate, the propagation conditions, the sensor itself, and the way information is processed. The article details several contributing factors:

• Atmospheric Conditions: The non-uniformity of the atmosphere, including temperature inversions and layers with varying refractive indices, can cause radar waves to bend or refract in unexpected ways. This is particularly relevant in phenomena like "super-refraction," where waves are bent beyond the normal horizon.
• Sensor and Equipment Limitations: The sensitivity of radar receivers has increased dramatically, but this also means they can pick up unwanted signals. Techniques like Doppler effect compensation are used to filter out ground echoes, slow-moving targets, and clutter, but these systems themselves can sometimes malfunction.
• Interference and Cross-talk: Radar stations can interfere with each other, especially if they operate on similar frequencies or have overlapping beam patterns. This can lead to "angel echoes" that appear as targets but are actually reflections or signals from another radar.
• Internal Equipment Issues: As seen with the example of solid-state delay lines replacing older mercury delay lines, internal components can introduce parasitic signals, leading to phantom targets.

Historical Cases and Examples

• "Angels" (50s onwards): Reports of "angels" were common in the early days of radar, often later identified as flocks of birds, insects, or atmospheric phenomena like "thermal cells." The US early warning system was famously alerted by "unknown targets" that turned out to be bird flocks.

• Warsaw Pact "Angels" (May 26, 1974): A radar station in the DDR detected a target approaching from the west, which was tracked by multiple stations at speeds of 80-100 km/h. An interceptor pilot saw nothing, and the targets eventually disappeared. Investigations suggested interference from a distant radar station and atmospheric conditions, possibly tropospheric ducting, as the cause.

• Rostock Anomalies (July 15, 1982): Radar screens in Rostock showed "angel echoes" and "fast flying targets." These were later attributed to interference from a radar station over 150 km away, with atmospheric conditions enabling a tropospheric connection. The images also showed coastal outlines due to strong super-refraction.

• Helicopter Phantoms: Situations where targets initially identified as helicopters were caused by hot slag being dumped into water, creating rising metallic "bubbles" that produced distinct radar echoes.

• Extended Range Echos: In summer, abnormal over-reaches with echoes from distant coastlines (e.g., Danish islands, Sweden), ships, ferries, and even "moving" express trains were observed, attributed to inversions and super-refraction.

• "Fast Flying Targets" (Cold War Era): DDR radar operators detected "fast flying targets" with unusual paths that were not confirmed by height finders. These were eventually explained as interference from neighboring radar stations operating in a bistatic or multistatic mode, where signals were scattered and received by a different station.

• Internal Causes: The article also mentions cases where phantom targets were generated by internal equipment issues, such as a training simulator not being switched off.

Science & Technology News

This section includes two brief news items:

• Senior Astronaut Begins Tests (November 2, 1998): US Senator John Glenn, the oldest person to fly in space, began experiments aboard the Space Shuttle Discovery. Scientists aimed to study the aging process and sleep disorders in microgravity, with experiments including blood analysis, protein studies, and extensive sleep monitoring.

• Asteroid Gets a Visit (October 26, 1998): The "Deep Space 1" spacecraft, equipped with a new ion engine using Xenon gas, was launched to visit a distant asteroid. The mission utilized advanced technologies, including an "electronic brain" for navigation, costing approximately 250 million Marks.

Recurring Themes and Editorial Stance

The recurring theme throughout the "Radar-Anomalie" report is the explanation of unexplained radar contacts, often labeled as "UFOs" or "angels," through conventional physical and technical means. The magazine emphasizes that while these phenomena can be puzzling and sometimes lead to misinterpretations, the majority have plausible explanations rooted in atmospheric physics, radar technology limitations, or interference. The editorial stance appears to be one of critical investigation, seeking rational explanations for anomalous observations rather than immediately resorting to extraordinary hypotheses. The article concludes by advising caution when using radar data as evidence in UFO investigations, suggesting that such data should ideally be corroborated by visual or other sensor-based confirmations.