Radar antenna

The largest application of polycyanurates is in circuit hoards. Their transparency to microwave and radar energy makes them useful for manufacturing the housing of radar antennas of military and reconnaissance planes. Their impact resistance makes them ideal for aircraft structures and engine pistons. ... 

The domestic microwave oven is a serendipitous invention. Percy Spencer was working for Raytheon, a company heavily involved with radar during World War II, when he noticed the heat generated by a radar antenna. In 1947 an appliance called a Ra-darange appeared on the market for food processing. The first kitchen microwave oven was introduced by Tappan in 1955. Sales of inexpensive domestic ovens now represent a multibillion-dollar (euro) annual market. 

Assuming that the target reflects all illumination power omni-directionally, the power received by the receiving radar antenna with effective surface Sr is equal to... 

In Sperry-Rand Corp (12) vs. Electronics Concepts, Inc., et al. the ex-employees had taken valuable data on radar antennas. One had learned what he knew at Sperry-Rand and went into competition with Sperry-Rand—even competing on a government bid with stolen knowledge of the exact amount of the Sperry-Rand bid. Both damages and an injunction were awarded to Sperry. These ex-employees willfully and deliberately and with full knowledge of the unlawfulness of their acts took both technical and financial data. 

Servomechanisms are an important part of nearly every pieee of modem mechanized Army equipment. They are used to automatically position gun mounts, missile launchers, and radar antennas. They aid in the control of the flight paths of jet-propelled rockets and ballistic... 

Parabolic reflectors are used in other devices as well. Radar antennas, the dishes used to pick up satellite television signals, and the reflectors used to concentrate sound from distant sources are all parabolic. 

The solid curves in Figure 5 (160 mm h 1 rain rate) show that the raingenerated ring waves are the main scatterers at wind speeds up to 8 m s 1. It was already shown by Braun et al. (2002) that the occurrence of two peaks in the Doppler spectra (measured at co-polarisation) is caused by ring waves propagating towards and away from the radar antennae. These ring waves cause two separated peaks with an overall (mean) Doppler shift due to the wind-dependent surface drift. 

The measurements were carried out in the wind-wave tank of the University of Hamburg, which is 26 m long and 1 m wide. The mean water depth is 0.5 m, the wind tunnel height is 1 m, and the effective fetch is 19.5 m. The measurement area was at a fetch of 15.5 m. The scatterome-ters used for the present investigation are working at 9.8 GHz (X-band) and 37 GHz (Ka-band) and the measurements were carried out with upwind looking radar antennae and at W-polarisation. 

Radar is the acronym for radio detection and ranging1. This means that electromagnetic waves are used to measure the distance between a radar antenna and an obstacle. The simple form of the radar equation expresses the maximum radar range Rmax in terms of the key radar parameters and the radar cross section of the target. 

The radar antenna, in addition to transmitting and receiving the radar waves, is responsible for the focussing of the millimeter waves. In principle, planar antennas, lens antennas, or reflector antennas can be used. Today, monostatic lens antennas are commonly in use. 

Figure 7. Cross sectional view of transmitted electromagnetic signal generated from ground penetrating radar antenna transceiver.

To preserve the reflection signal, a long decay phosphor is required. The phosphors used in the past were generally composed of two phosphors, one with a long decay. Thus, the screen exhibits two colors, that of the target and the other forming the background which is refreshed in every 360 ° rotation of the radar antenna. Radar phosphors include ... 

It was mentioned in sub-section 13.5.2 that the cut-off frequency for effective screening is in the range of 0.5 kHz to 2.0 kHz for external interference. At frequencies higher than about 1 MHz it is useful to consider the coupling between the screen and the core as an impedance that relates the screen current to the core open-circuit voltage. In such a case it is not specified how the current appears in the screen. It could be by mutual induction from nearby cables, but more often by radio waves received from local radio transmitters, radio telephones, or a radar antenna. The impedance is called the shield transfer impedance Zj and it can be measured by a relatively simple test procedure. The expression for the impedance Zj is -... 

Components produced by shear forming are mainly parts for the automotive and aerospace industries, along with art objects, musical instm-ments, and kitchenware. Typical examples are jet engine and turbine components, dishes for radar antennas, and domestic utensils. The process is capable of forming components of diameters ranging from 3 mm to 10 m, and thicknesses of 0.4-25 mm (Brown 1998). Figure 1 shows the main features of the process and examples of obtainable geometries. 

Radar Antenna Vulnerable Elements Radar Counter-Countermeasures Chaff... 

The feed provides an output for the transmitter and input to the receiver depending on which function the radar is performing. The principle of reciprocity dictates that the transmit and receive antenna patterns are identical. This condition generally holds true for radar antennas unless there are nonlinear components in the antenna (such as ferrite devices) or the illumination function described in the following is dehberately changed between transmit and receive. Hence, the antenna will generally have the same polarization on transmit and receive. 

Construction elements for magnetohydro-dynamic generators Dielectrics for radar antennas V V V... 

Figure 1-7. Examples of plastics in the electrical and electronics field a) snap-in cable set of plugs and adapters, using Amoco s Ardel D-lOO polyarylate b) plastic parts in a sixty-ft.-diameter high-precision, high-frequency antenna c) schematic of a reinforced plastics/ composite radome that protects a 150-ft.-diameter radar antenna from its Maine environment view of reinforced plastics sandwich geodesic radome being assembled the completely assembled radome d) space-communication antenna. The horn of plenty uses an RP sandwich in its reflective panels (glass-fiber-TS polyester skins with a kraft paper-phenolic honeycomb core). It has a two-ply air-inflated Du Pont Hypalon/Dacron fabric elastomeric radome that will protect the antenna from the outside environment for many decades and uses other plastics. This site in Maine was the world s first ground-to-ground conununication satellite.

Figure 9.3 Sea salt deposited on the external surface (a) of a Cormorant sea and rescue helicopter radar antenna, and (b) salt causing corrosion to the internal components of the antenna due to a broken seal. (Courtesy Major S.J.R. Giguere)...

---