Radar’s impact on modern warfare has been tremendous because it has . virtually eliminated the element of surprise due to concealment in darkness, fog, cloud, or artificial smoke. It ranks second only to the atom bomb in developments of the past war which are tending to revolutionize naval warfare. It used to be that naval battles were decided by the factor of who happened to be “up-sun” from the enemy. Now our ships slug through whole engagements in which the enemy may be detected, ranged on, and sunk without a single man having seen him visually. During such a battle, our ships may be traveling in rigorously kept formation at high speed through narrow waters, but they “see” one another and the shore, by radar. Now, our bombers are no longer grounded by bad weather at the home fields or at the target area. Not only can they navigate unerringly to the target area, but also they can line up on the target and bomb by radar alone, and even guide specially constructed bombs to the target itself.
Let’s make a survey of the subject and see if we can properly evaluate this miracle of electronics.
History
The beginning of interest in radio detection as a military device can be dated from communication experiments carried on around 1922 by two civilian scientists working for the United States Navy. They suggested to the Navy that, with radio detection equipment, ships on a line a number of miles apart could be immediately aware of the passage of an enemy vessel between any two ships on the line, irrespective of the visibility.
The principle of determining range by sending out pulses or bursts of radio energy, which characterizes modern radar, was first used in 1925 for measuring the Kennelly- Heaviside layer, part of the ionosphere.
In the summer of 1930 the art of radio detection took another step forward when U. S. Navy scientists discovered that a pattern of radio waves showed considerable interference when a plane passed between the transmitter and the receiver. Up to this time, however, regular radio waves rather than pulses were used, necessitating bulky equipment with a considerable distance separating the transmitter and the receiver.
In April, 1937, radar worked over salt water at the mouth of the Chesapeake on the old four-stack destroyer Leary. The next two years were spent in designing a practical shipboard model. A set operating on a wave length of a meter and a half was installed on the U.S.S. New York in December, 1938.
The Army and Army Air Forces were, of course, making concurrent experiments.
By the end of World War II, Navy requirement had increased from the single radar installed on the destroyer Leary to 22 radar sets on a modern battleship.
British radar was developed at about the same time as the American systems, but at a somewhat faster pace under the immediate threat to Britain’s security. At the time of the Munich crisis the whole east and southeast coast of Great Britain was manned. By 1940 radar art was sufficiently advanced to give British pilots a three-dimensional location of the enemy—range, azimuth, elevation—and an estimate of numbers. This gave the Royal Air Force all the essential data to enable them to win the Battle of Britain against the great numerical odds of the Luftwaffe, and to deserve Churchill’s: “Never have so many owed so much to so few.”
The efforts of American and British laboratories were combined in 1940. By the time of the Japanese attack on Pearl Harbor the U. S. Navy had already installed on key ships not only radar for aircraft warning, but also radar for surface search and fire control, while the Army had in the field numbers of long-range aircraft warning sets, as well as antiaircraft and searchlight batteries equipped with radar.
Today Army and Navy radar requirements are coordinated to the point where many sets and nearly all component parts are made interchangeable between the services. The original Signal Corps and Navy nomenclature has been superseded for new equipment by a joint “AN” (Army-Navy) system in which all sets or components developed for either service are given the same nomenclature in the supply catalog of both.
From our enemies no new principle or radio device has emerged, and for the most part both Germany and Japan were content to follow industriously in the footsteps of the Allies, literally “picking up” what inevitably has come into their possession from time to time.
Theory of Radar
Massachusetts Institute of Technology, one of the leaders in the field of radar, offers this definition of radar: “Radar may be defined as the art of determining by radio echoes the presence of objects, determining their direction and range, recognizing their character, and employing the data thus obtained in the performance of military or naval action.”
The official United States derivation of the word “Radar” is that it means RAdio Detection And Ranging.
A radar set accomplishes the detection of targets by sending out pulses of ultra-high frequency radio wave energy from a high- power transmitter. These pulses are concentrated into a beam (similar to a searchlight beam) by a directional antenna. When the transmitted energy strikes an object, a portion of it is reflected in much the same manner as the sound waves echo from the face of a cliff. This echo energy is detected by the receiver through its antenna and is translated into usable information on indicators. The fact that radio waves travel at the constant velocity of light enables us to determine the range, and the fact that the receiver antenna is directional enables the determination of azimuth and elevation.
Components
While there are many different types of radar sets, fundamentally they all consist of six essential components:
(1) Transmitter. This transmits the ultra-high frequency in short, powerful pulses.
(2) Receiver. This receives the weak echoes returned and sends them to the indicator(s).
(3) Antenna System. This takes the energy from the transmitter, radiates it in a directional beam, receives the echoes, and passes them to the receiver.
(4) Indicator(s). This produces a visual readable indication of the echoes.
(5) Timer. This is the synchronizer of the whole system which times the transmitted pulse and the indicator(s).
(6) And, of course, a Power Supply is essential.
In radar, unlike conventional radio sets, the transmitter and the receiver are located at the same place. Prior to the discovery of radar, many successful experiments had been made with radio direction-finding. However, in these trials the distant object had to send radio waves to one or more distant radio stations. These latter could then fix the position of the distant object. Obviously such a system has little application in the detection of targets under battle conditions.
Principle of Operation
Mention has already been made of the fact that range is determined by the measurement of the time taken by a radio wave to be transmitted and echoed back. The method of doing it is complex, or perhaps radar would have been developed much sooner.
The cathode-ray tube is a special type of vacuum tube which acts as an electronic stop-watch. The electrons are formed into a narrow beam so that the cathode-ray tube acts as a hose directing the stream of electrons at a screen which glows at the point where the electrons strike. The beam of electrons is made to sweep across the fluorescent screen in somewhat the same way as a hand sweeps across the face of a clock. Just as the second hand of a clock completes its sweep of the face in sixty seconds, the electron beam can be made to travel across any desired portion of the fluorescent screen in some predetermined interval of time. For example, let us assume that the maximum range of the radar set we are discussing is 186 miles. Then if the beam is made to travel across the screen in 1/500th of a second, we might graduate the face of the cathode-ray screen and put 0 miles at one end and 186 miles at the other end of the sweep.
We know that radio waves travel at 186,000 miles per second. The distance traveled by a pulse to and from a target is twice the actual distance to a target, since we must allow equal amounts of time for the initial transit and the echo. In the case of our set with a target at maximum range this will be 186 miles X 2, or 372 miles. This divided by the speed of radio wave travel, which is 186,000 miles per second gives 1/500 second as the time required for the radar impulse to travel to the target and echo back. As the waves travel at a constant speed, we can graduate the whole line into a uniform scale of miles. Actually, we will not be able to detect such a sweep across the screen since the eye cannot detect such a rapid movement. The screen is of a persistent nature so that it glows for a time interval after the beam has passed to another portion of the screen. Because the sweeps are so rapid, the beam is repeating the sweep before the glow dies out, and a single, solid, horizontal line is presented to the eye.
The returning echo is picked up by the sensitive receivers and makes the electron beam deflect as it sweeps across the screen. This makes a “pip” in the line at a point representing the time for the echo to return. This type of scope is called an “A” scope.
The accuracy with which time is measured determines the accuracy of the range. To obtain a range accuracy of three yards, time must be measured to an accuracy of a hundred-millionth of a second. When time is measured to this accuracy, the range is then accurate to three yards regardless of whether the range is 30 or 30,000 yards. This is in contrast to most other types of range finders, which have a constant percentage error in determining range.
The use of timed pulses, as we have seen, gives a simple means of measuring range. How then is the direction in which a target lies determined? This is done by providing the radar with a directional antenna, which sends out the pulses in a narrow beam, like a searchlight. Since bearing and elevation determination are similar, only bearing determination will be discussed here. There are in use two systems, the single lobe and double lobe.
In the single lobe system all energy is directed in a single lobe. The antenna may be rotated as the pulses are sent out, and we get back a “pip” when the antenna is pointed toward its target. We get the strongest pip when the beam of energy sent out by the radar is pointed directly at the target. The bearing of the center of the antenna gives us the azimuth of the target.
The method used in most fire-control sets for bearing determination is a double lobe system. Two identical lobes whose axes are displaced by some fixed angular distance are used. The two lobes intersect at only one point, known as the crossover point. Each lobe receives a pip from the target. When the two pips are of equal size the antenna is pointed directly at the target. The use of two lobes instead of a single lobe greatly increases the precision of bearing measurement because the operator has a more sensitive indicator to show whether or not he is off target. In addition, it provides the operator with a sense of direction. If the antenna is off target, the inequality of the pips shows him the direction to turn. These advantages are obtained at a loss of maximum range of the radar. Hence the single lobe system is most often used in search sets, while the double lobe system is usually employed in fire-control systems.
Antennas are made directional by building them up of an array of small antennas suitably spaced and timed to concentrate the energy in one direction; or they may be built on a searchlight principle of spraying the energy into a large parabolic reflector which focuses the energy into a beam.
Indicators
Cathode-ray tube indicators may be subdivided into two general classes. In one, termed “deflection modulated,” the echo shows as a deflection in a bright line.
The second, termed “intensity modulated,” is exemplified by PPI and B Scopes.
The PPI (Plan Position Indicator) shows, in polar coordinates, a radar map of the area being covered, with the set at the center of the screen. Range is indicated by the radial distance from the center of the screen at which the echo appears.
The B Scope also presents range and bearing on the same scope.
In intensity modulated scopes, echo signals are made to appear as bright spots. It is not like television; the blobs do not look like ships or planes, but they are interpretable as such by a trained operator. Other types of indicators have been developed and are in use, but these are the most frequently encountered types.
Capabilities
Radar equipment is capable of detecting the presence of objects in the air and on the surface, and of measuring their range, bearing, and elevation—under certain conditions. Radar cannot locate completely submerged submarines.
Shipborne Radar sets may be grouped generally into two classes:
(a) Search
(b) Fire-Control
The requirements for each of the types of radar differ widely. Search sets need a long range but only a fair amount of precision, since their primary function is warning. Search sets should have a high degree of resolution to enable targets to show as separate indications.1 Fire-control sets must be able to determine range, bearing, and altitude with a precision greater than that of the guns with which used, in order to achieve destructive gunfire; and the radar should be capable of distinguishing between two very close plots, thus permitting spotting.
Different types of radars are therefore designed with fundamentally different characteristics to allow them to perform their primary function best, this function generally being achieved at the expense of other functions.
The pips that appear on a radar indicator show only the presence of a target within the field of view of the radar. The position of the echo signals on the screen indicates range and azimuth. To the untrained operator, the echo from one ship looks like the echo from any other ship. However, with proper training the operator will often be able to estimate the type of ship detected.
A knowledge of the operating characteristics of a particular radar set is necessary before the capabilities or the limitations of the set can be appreciated. There are properties inherent in a radar that limit the precision with which data can be measured. Additional limitations imposed by operating conditions may reduce radar accuracy considerably.
Limitations Imposed on Radar by External Factors
If it is assumed that radio waves travel along perfectly straight paths, the curvature of the earth prevents these straight rays from striking objects that are beyond the horizon. If the height of the antenna is increased, the horizon is extended. An object beyond the horizon can be seen if it is sufficiently high that the ray tangent to the earth can strike it. Radar waves, like light waves, are bent when they pass through a non-homogeneous medium like the atmosphere. Since the water vapor in the atmosphere bends radio waves almost twenty times more than light waves, the distance to the apparent horizon for a radar set is approximately 15% greater than the distance to the optical horizon.
Not all of the radar waves travel to the target in straight lines. Hence, energy arrives at the target at the same time from different paths. The effect of this phenomona is to cause complete cancellation at certain points in the field. These points are called “nulls.” Thus, the result of reflection of radar pulses from the sea or other reflectors is to break the vertical antenna pattern into many rather narrow lobes which are separated by the nulls. This double path of travel actually almost doubles the range at which a target may be detected, since the pulse energy which can get to the target by the two paths is stronger than that which reaches it by the single direct path.
The width of an antenna beam in either the horizontal or vertical dimension is determined by the width and height of the radar antenna in wave lengths.
The sharper the beam, the more concentrated the energy, and therefore the greater the range obtainable with a given amount of transmitted power. The narrower the beam, the greater the azimuth accuracy and azimuth resolution that is possible. Thus low-frequency radars have relatively poor azimuth accuracy and azimuth resolution, because the antenna beam cannot be made very sharp. Although a radar antenna is highly directional, not all of the radiated energy is confined to the principal beam. In spite of the fact that the radiation far off the axis of the main beam is small, it is still sufficient to produce strong echoes from large, nearby targets. Many a round was fired at galloping ghost targets off Oahu, caused by side lobe echoes from a nearby mountain.
The atmosphere does not appreciably weaken radar waves if the wave length is above 10 centimeters. However, the attenuation caused by absorption becomes 'increasingly more important as the wave length decreases. In some of our shortest wave length sets there is a noticeable decrease in range to approximately 50% of maximum during rainy weather.
Echoes are sometimes received from wooden boats, birds, fish, and clouds, especially with microwave radar. Sea gulls caused some anxious moments in the early days of the war. The amount of energy reflected back to the radar is nearly proportional to the effective area of the target, as long as the target is large compared to the wave length of the transmitted energy. Very small targets, such as submarine periscopes and small buoys, can therefore be detected at much greater range with microwave radar than with long wave.
A radar target is never a single point. If it is a large object, it is composed of a number of variously oriented surfaces and corners, each of which is responsible for a little of the echo returned from the target. As the target changes aspect, the echo power may vary by a factor as much as 100.
A special case of reflection takes place when radiation is directed at an object composed of two plane reflecting surfaces which are at right angles. Such a reflector is called a corner reflector. A reflector of this sort will produce a very strong echo on a radar, because the energy that strikes the corner is reflected back directly to the radar without the excessive scattering that occurs with most targets. Metal corner reflectors are used often as artificial targets. Other uses are on aerological balloons that are tracked by radar, on special radar buoys, as artificial targets for use in boresighting radars, on life rafts, and in target sleeves.
As microwave radars have come into general use in recent years, the cloud or storm echoes that are frequently seen on the indicators have attracted attention. The possibility of using microwave radar as an aid to meteorological forecasting was recognized and it is now being put to operational use.
Effect of Weather
Radar detection ranges are pronouncedly affected by meteorological conditions. Enemy ships far beyond normal radar range have been located by radar and sunk by radar- controlled fire. Convoys have been tracked on some occasions to 100 miles beyond normal radar range. On the other hand, the same radar sets a few hours later have failed entirely to pick up targets clearly visible to the eye. Experiments have shown large variations in performance of a particular radar set over a three day period. At all times during this period the set was in excellent electrical condition. Hence it may readily be seen that serious errors and false evaluation of radar presentation may result if the effect of weather and atmosphere are not considered.
The effect of weather may be to:
(1) Increase the range of detection for surface vessels and low flying airplanes
(2) Reduce the range of detection for surface vessels and low flying planes in some instances
(3) Cause errors in height finding
(4) Increase the extent of sea return clutter, and thus reduce the operation efficiency of radar equipment.
However, weather effects cannot be blamed indiscriminately for variable radar performance. In general, internal conditions or poor adjustment will cause greater changes in range performance than variation in weather. For example, the failure of an air search set to detect a high flying plane at short ranges cannot be attributed to abnormal propagation conditions, since trapping affects the detection of targets only at low angles above the horizon.
Countermeasures
Every new weapon in warfare of necessity soon produces a defensive measure. Just as the use of gas resulted in the gas mask, and the bomber fathered the need for radar, so too did countermeasures result against radar itself. The first large scale jamming of radar took place on February 12, 1942, when the Scharnhorst and Gneisenau passed through the English Channel under the very noses of the best Allied radar. The German ships were not seriously damaged by shore batteries because the jamming created a small panic among the radar operators so that the vessels were not tracked by radar, and they were invisible under the cover of the weather. In an effort to cut down the bomber losses from anti-aircraft fire over German-held territory, the Allies, too, got into the radar countermeasures business.
The new eyes which radar has supplied sometimes can be blinded by skillful countermeasures in much the same manner as ordinary vision can be blinded by the artificial use of a smokescreen.
In brief, the weaknesses of radar which can be exploited are these:
(a) Radar can be “heard” at a considerable distance
(b) Its location and operating characteristics can be determined
(c) Since the echo that radar receives from most targets is very weak, that echo may be obscured by sending out a strong jamming signal from the target
(d) Radars have difficulty in distinguishing between actual targets and false deceptive ones.
Countermeasures exploit all four of these weaknesses.
The enemy has two objectives in using radar countermeasures. First, he hopes to prevent us from obtaining any accurate or useful information about his forces by the use of our radars; second, he wishes to get information about our forces by listening to our radar. The radar countermeasures that may be used in accomplishing these purposes are of four types: jamming, deception, evasion, and interception.
Jamming is the deliberate production by the enemy of strong signals for the purpose of hiding his movements or position from our radar by obliterating or confusing the echoes on our indicators.
Deception is the deliberate production by the enemy of false or misleading echoes on our radar. Small targets may be made to appear like large ones, or echoes may be made to appear where no genuine target exists.
Evasion consists of tactics that are designed to take advantage of the limitations of our radar to prevent or postpone radar detection, or to avoid revealing the true position of an attacking force. If attacking enemy planes take evasive action, it may be impossible to determine the height at which they are flying or the planes may be detected too late for an adequate defense to be made ready.
Interception is the detection of radar signals by the use of a special receiver. By this means the enemy learns of our presence in his vicinity, and may determine our location and some of the characteristics of our radar. Since this form of countermeasure is passive per se, it will not be further discussed here.
The effect of radar jamming is to produce a confusing pattern on the screen of the radar indicator. An almost infinite variety of patterns is possible.
There are two general types of jamming—- electronic and mechanical. Electronic jamming is accomplished by the transmission of modulated radio signals, while mechanical jamming is performed by dispersing “Window” or some similar substance.
Several different devices fall into the category of mechanical jamming. The most common of these objects is called “Window” or “Chaff.” These are strips of metalized paper cut to approximately one-half wave length at the frequency to be jammed. “Rope” is the second of these objects, and consists of pieces of tinfoil about 400 feet long suspended by a string from a small paper parachute. The third is known as “Angel,” and consists of a very light corner reflector made of aluminum foil suspended from a parachute.
All forms of Window may either be dropped from aircraft or dispensed by rockets fired from ships. Chaff and Rope are dropped or dispensed in bundles, each bundle representing the signal return from a heavy bomber or a large ship.
From the standpoint of its use in the war, deception is one of the least important of radar countermeasures. Although it is possible to deceive radars by the use of electronic devices, the necessary equipment is difficult to design and operate.
However, the use of mechanical devices for deception is entirely feasible, and both the Germans and the Japs used deception techniques. For example, the Japs equipped sampans with reflectors so that they appeared to our radars like large craft.
Looking into the future, evasion is the least important of the radar countermeasures classes. During the past war, low-frequency range radars could not detect low flying targets at long range because the antenna pattern is such that the beam did not provide good low cover. Both the Allies and the Axis were fully aware of this limitation and frequently approached “on the deck.” Future radars may be logically expected to overcome this weakness.
Operational Limitations
The amount of reliable data that can be obtained from any radar is dependent to a great extent on the skill of the operator. Operators must combine high native intelligence and good visual acuity with great concentration, if radar is to be used to maximum benefit. In general, a skilled operator can detect a target at a greater range than an unskilled operator.
A radar antenna will have a clear field of view only when there are no obstructions in the path of the radiated energy. Care in siting will reduce these blind areas to a minimum.
Should energy be reflected from targets beyond the maximum range scale of the radar set, the echo will be presented at an incorrect range. This will be a second trip echo, and the true range to such a target will be equal to the indicated range of the scale plus the maximum range scale reading.
Obviously any discussion of radar performance assumes that the set itself is at peak performance, accurately calibrated and oriented. Echo boxes, now available for most sets, will indicate peak performance. Range calibrators come with most sets for careful range calibration.
IFF
No discussion of radar would be complete which omitted its most necessary adjunct, IFF—Identification of Friend or Foe.
Radar sets alone are not capable of identifying whether or not the detected target is friendly or hostile. Hence the need for identification equipment to work in conjunction with radar sets, especially those in a surveillance role, is apparent.
The system of identification in use in the Armed Forces of the U. S. today is really just a “baby radar” with some of the regular radar units missing. In one respect it is strikingly different, however. A radar set is a complete unit in itself in that no assistance is needed from the target to obtain an echo. In using an IFF system, a ground or ship based IFF unit receives a response from a unit borne by the friendly interrogated plane or ship.
It is the function of the ground-based portion to challenge the detected target and identify it as either friendly or hostile. Only friendly craft answer the challenge (providing they are equipped with the necessary unit).
Present IFF equipment serves only to decrease the number of unidentified craft detected by radar and, unfortunately, is not the complete answer to the problem.
IFF with all of its weaknesses is the only means now available for identification comparable to radar. Dr. Lee DuBridge, wartime head of the Services Radiation Laboratory at Massachusetts Institute of Technology, states: “This matter (identification) has been given a great deal of thought by some of the foremost thinkers in the electronics field, and for the immediate future no means of positive identification of friend and foe appears practical. No matter how short the wavelength used, no electronic apparatus can hope to approach the capabilities of the human eye. And even identification by the eye leaves much to be desired.”
The Future
Obviously the first goals will be radar sets which can overcome some of the limitations of present sets.
Although much of the effect of countermeasures may be nullified by proper training and indoctrination of radar operators, it is essential that future radar sets incorporate the best known safeguards against radar jamming. Large strides have been made in this direction and it is reasonable to expect more in the future.
It does not appear feasible to expect to hide radar sets in the future. However, the betraying of our own position by radar operation is not a serious limitation. When tactical surprise is desired, sets may easily be turned off.
Since the first radars appeared, a great deal of progress has already been made in the elimination of nulls and dead areas. We may expect more success in this direction.
Several different devices are in various stages of perfection for the elimination of ground clutter and other fixed targets. While such devices of course will not allow a radar set to see through a nearby mountain, they will greatly assist in preventing a plane from hiding in the clutter on the scope until it has accomplished its mission.
As far as weather is concerned, it is predicted that the biggest steps in overcoming any adverse affects of weather will be made by the users as experience is obtained in the field.
Designers, by the proper selection of frequency and other operational characteristics, will be able to overcome most of the range and azimuth limitations in a particular set for a particular purpose.
A great deal of effort and money was spent during the war on IFF without producing an entirely satisfactory identification device. Let us hope that the future brings forth an answer to this perplexing problem. It is felt among many electronics men that a radical departure from IFF will be the answer.
Civilian Use
There has already been a great deal of rather uninformed speculation about the peaceful uses of radar. The direct and immediate use of radar in civilian life will be to make air and sea navigation entirely continuous and foolproof, regardless of night or weather. Radars will probably be installed on every ship at sea, and on every tug and ferryboat in harbors. They should prevent collisions in fog and with icebergs, and permit a ship to sail safely into any harbor in the world irrespective of the weather. Similarly, airplanes should be able to fly over mountain ranges and New York’s skyline in storms without mishap, for their position above the mountains and buildings will be known at all times with a radar. Ground controlled approach radar will permit airplanes to effect blind landings at any airport in bad weather, day or night, and to avoid collisions with other aircraft. Teleran (Television-Radar-Air Navigation) will permit the transmission of ground radar information to the aircraft, as well as weather maps, ceiling and visibility information, and traffic instructions.
On the other hand the application of radar to land transport, trains, and automobiles, seem to have little immediate application. One of the characteristics of radar use is that the ultra-high frequency radio waves used in radar travel in comparatively straight lines and cannot see around corners or over hills, and hence radar could contribute little to the safety of land transport.
Military Use
In the field of Military Science, however, radar appears to be destined for an even greater number of uses. Obviously all of the above safety measures suggested for civilian use will be applied directly to military fields.
Perhaps the most logical development of radar equipment that can be anticipated is lighter, smaller equipment. Great strides have already been made in this direction. Greater accuracy, ruggedness, dependability, and simplicity of operation are all ends that may well be achieved. It is to be anticipated that radar sets used for target detection and fire control will be integrated more closely into the computor-data transmission- gun team. Such an integration may well include the communication system of the firing unit, and even a radar chronograph operating on the Doppler principle.
But the field of guided missiles offers the broadest and most important one for radar and other electronic devices. Radar devices seem to be the main hope for defense against this type of weapon, and undoubtedly radar or some other electronic device will be used in the offensive control of them. It is a well known fact that the U. S. Navy achieved some success in this field during the war.
The contact of the moon by radar has practical values. To science it means that the moon may eventually be mapped. Refined measurements can be made of the speed of light, the speed of the moon, and the distance to the moon. But the most important scientific fact thus established is that the various layers of the atmosphere—some of them bearing electrical charges—can be penetrated by a radio wave. Since rocket missiles travel outside the earth’s atmosphere, it was not certain that radar could track them. That doubt has been removed. Similarly, long range jet or rocket missiles might be radio controlled from the earth.
Conclusions
The biggest influence on civilian life radar will have is indirect. The thousands of man- years which have gone into the improvements of the detailed components which make up a radar set—many of these components being identical with those of a radio or television set or hearing aid, or other electronic device—have made obsolete many of our pre-war ideas about what could and could not be done in electronics.
Altogether it is fair to say that radar, as radar, will have a mild beneficial effect on all our lives as civilians by making it safer to travel by sea or air. But the impact generally of electronics techniques developed during the war because of radar will have profound effects on the shape of our daily life.
As regards the naval man, he may reasonably expect radar to enter into almost all phases of combat, both offensively and defensively, in many different forms, doing a multitude of diverse tasks. No matter what job he is performing, he may expect to come into direct contact with radar in some of its many forms. And certainly the staff officer will meet, and meet again, radar doing a myriad of jobs throughout all the armies and navies of the world.
1. Resolution is defined as the ability to distinguish between targets that are close together.