LECTURE 6 RADAR PART II

Introduction Recall Back RADAR Part 1  What are the three types of RADAR?  What are the differences between PSR and SSR?  How PSR works?  How SSR works?

why ‘Stealth’ aircraft can be invisible ?? B-2 Spirit stealth bomber of the U.S Air Force An F-117 Nighthawk stealth strike aircraft

Most conventional aircraft have a rounded shape. This shape creates a very efficient radar reflector. Means that no matter where the radar signal hits the plane, some of the signal gets reflected back

However, some military aircraft are designed and constructed to be non-reflective - the so-called “stealth aircraft”. B-2 Spirit stealth bomber of the U.S Air Force An F-117 Nighthawk stealth strike aircraft

A stealth aircraft is made up of completely flat surfaces and very sharp edges. When a radar signal hits a stealth plane, the signal reflects away at an angle. Surfaces on a stealth aircraft also can absorb radar energy as well. So, this aircraft become invisible.

2. Airborne Weather RADAR (AWR)

Introduction  Airborne Weather Radar (AWR) is used to provide the pilots about weather ahead.  The installation include weather radar antenna located in the nose of the aircraft and weather radar display inside the cockpit.  The radar information can be displayed in combination with the aircraft route on the EFIS Navigation Display (ND)  Weather radar is used for severe weather avoidance

The antenna is housed in a radar made of composite materials located in the nose of the aircraft.

How Airborne Weather Radar Works  An antenna which sweeps side to side transmits Super High Frequency (SHF) signals which is 9Ghz  When hit the reflective objects (precipitation), the signals is reflected back to the antenna receiver.  The returns (echo) are displayed to the pilot on the aircrafts radar screen.

Precipitation  Weather radar is function to detect, locate, and measure the amount of precipitation.  Precipitation is within or falling from cloud.  It includes rain, snow, ice & hail.  Different precipitation has different refractive and reflective levels.

Airborne Weather Radar Works  The goal of weather radar is to display areas of heavy precipitation, which generally indicates areas of turbulence.  Different types of precipitation have different reflective qualities.  Reflectivity of precipitation is directly related to MOISTURE content.  Large water droplets show the strongest returns, while dry hail or snow will show light returns, or no returns at all.  Weather radar detects raindrops, not clouds or fog.

Airborne Weather Radar Works  The precipitation painted (depicted) by airborne weather radar is not of primary concern, however it is representative of areas of severe weather.  Areas of large raindrop size=high rainfall rate=intense storm=turbulence.  The turbulence associated with convective clouds is often severe and always dangerous.  Other dangerous factors associated with thunderstorms are: severe icing, hail, lightning, strong downdrafts.

Airborne Weather Radar Display

CAUTION: weather radar emits harmful radiation, it should not be operated when people are standing within 50 feet of radome or during refueling.

Radome Radome is a dome- shaped protective enclosure for a radar antenna, made from materials that do not interfere with the transmission and reception of radio waves.

Radome

Conclusion  Properties of wave are very essential for a better understanding on how radar and other instruments works.  Radar is very useful for navigation purposes, safety purposes and very helpful as well in airport management.