RADAR is an electromagnetic system for the detection and location of target objects such as aircraft, ships, spacecraft, vehicles, people, and the natural environment which can reflect a signal back. It uses electromagnetic radio waves to determine the angle, range, or velocity of objects. RADAR was developed by various nations before and during Second World War. RADAR is a classic example of an electronic engineering system that utilizes many of the specialized elements of technology practiced by electrical engineers, including signal processing, data processing, waveform design, electromagnetic scattering, detection, parameter estimation, information extraction, antennas, propagation transmitters, and receivers. This paper gives an outline of RADAR principle and some of the RADAR applications, which range from air traffic control, forest and climate monitoring and the monitoring of natural disasters, to name just a few.

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1Closed Loop Control of Soft Switched Forward Converter Using Intelligent Controller

IJCTA, 10(03), 2017, pp. 1-9

© International Science Press

RADAR and its Applications

Niraj Prasad Bhatta* and M. GeethaPriya**

Abstract : RADAR is an electromagnetic system for the detection and location of target objects such as

aircraft, ships, spacecraft, vehicles, people, and the natural environment which can refl ect a signal back. It uses

electromagnetic radio waves to determine the angle, range, or velocity of objects. RADAR was developed

by various nations before and during Second World War. RADAR is a classic example of an electronic

engineering system that utilizes many of the specialized elements of technology practiced by electrical

engineers, including signal processing, data processing, waveform design, electromagnetic scattering,

detection, parameter estimation, information extraction, antennas, propagation transmitters, and receivers.

This paper gives an outline of RADAR principle and some of the RADAR applications, which range from

air traffi c control, forest and climate monitoring and the monitoring of natural disasters, to name just a few.

Keywords : RADAR, applications, electromagnetic,surveillance, synthetic aperture.

1. INTRODUCTION

RADARis an electromagnetic system which is used for sensing, detecting and locating the objects present

in the ambience. RADAR stands for Radio Detection and Ranging. For the fi rst time, in the year 1940

US Navy coined the term RADAR. This system operated by transmitting an electromagnetic wave and

detecting the refl ected signal. Earlier, the RADARwas mainly developed for detecting the existence of a

target for measuring its range, so addressed as RADAR. During the Second World War, it was fi rst used to

notify the approach of hostile aircraft and for routing antiaircraft weapons. The modern RADAR system

can be used to extract much more information from the refl ected signal and got broader applications but

still the range detection is one of its important functions. Till now, there is no electronic system which can

replace the RADAR for its accuracy and effi ciency in sensing and detection.

RADAR extends the capability of sense of vision by observing the atmospheric conditions. It can

observe the environment conditions that are impervious to the human vision. It can be envisioned as

an additional sensory organ to the human eyes that can detect and locate the object beyond the reach of

human eyes. Its attribute can be seen in collecting data in rain, snow, darkness, fog, smoke, etc. It is also

used to measure the instantaneous velocity of any object approaching or going away from the observer.

RADAR radiates either radio waves or microwave signals and receives back the refl ected signal. A most

common type of waveform radiated by RADAR is the train of narrow, rectangular shaped pulses.

In present days, the high tech RADAR has wider areas of applications, viz. aircraft anti-collision

systems, air and terrestrial traffi c control, surveillance systems, air-defense systems,meteorological

monitoring, antimissile systems, RADAR astronomy, marine RADARs for ships, guided missile target

locating system, remote sensing, geological observations, measurement of height and depths etc.

RADARhas become a high-end security system on which surveillance of entire world depends and

becoming more and more popular nowadays. Radars have been deployed on ground, on sea,in air, and in

* Department of Electronics & Communication Engineering, Jain University, Bangalore, India, E-mail: sky4drmzz99@gmail.com

** Centre for Incubation, Innovation, Research and Consultancy (CIIRC), Jyothy Institute of Technology, Bangalore, India E-mail:

geetha.sri82@gmail.com

2 Niraj Prasad Bhatta and M. GeethaPriya

space for detecting and locating objects.In this paper, the authors discuss about the RADAR principles and

applications highlighting the importance of RADAR in day to day life. In this paper, section 2 deals with

the concept of RADAR principle and its operation, section 3 & 4 gives the basic types and classifi cations

of RADAR followed by RADAR applications in section 5.

2. PRINCIPLE AND OPERATION

The basic principle of on which RADAR operates is similar to that of sound wave refl ection. RADAR

uses electromagnetic energy pulses for detection and location of the objects. In short, its operation can be

summarized as below:

• The RADARtransmitselectromagnetic waves through the antenna in all the directions.

• Refl ecting objects (targets) intercept these radiated waves and refl ect back in all the directions.

• Some of the refl ected signal is received by the receiver in RADAR system.

• The received signal is processed further through digital signal processing and amplifi cation

thereby a decision is made at the reception output for determining the presence of refl ected signal

from the target. If the target is present, its location and other information are obtained.

Antenna

Duplexer Power

amplifier

Waveform

generator

Low-noise

amplifier

Local

oscillator Mixer If

amplifier

Matched

filter

Second

detector

Video

amplifier Display

Figure 1: Block Diagram of Elementary RADAR system

The Figure 1 shows the block diagram of a elementary RADAR [1]. The power amplifi er is used as

a transmitter which produces suitable signal to radiate. It may be an average power or the high power

amplifi er. Generally, short pulse signal are produced by RADAR. Duplexer allows a single antenna to be

used for both transmission and reception of signals. It also protects the receiver from burning out. The

antenna acts as a transceiver system. It transmits the electromagnetic radiation in the space and receives

back the refl ected signal. Mostly directive antennas are used because of its property of collecting a weak

echoed signal. Also, it acts as a spatial fi lter to provide angle resolutions. The receiver of RADAR system

is a heterodyne system. It consists of series of steps for signal processing for target detection. The fi rst

stage consists of either low noise amplifi er or the mixer stage. The receiver input with low noise amplifi er

is more sensitive to the signal detection. And if mixer stage is deployed as an input, it provides greater

dynamic range, less vulnerability to electronic interferences.

The receiver amplifi es the refl ected signal to a level where it can be easily analyzed. The clutter from

the refl ected signal (echoes) can be removed by using a receiver input with high dynamic range. The local

oscillator and mixer is used to convert the received RF signal to the IF (intermediate frequency) signal.

The RADAR used for air-surveillance, the IF amplifi er has a center frequency of 30MHz or 60 MHz with

a bandwidth of 1MHz. The IF amplifi er is designed as a matched fi lter (i.e . the signal-to-noise ratio at

output is maximized) for signal processing. It separates the desired signal from the undesired signal. Then,

the pulse modulated signal is received by second detector and amplifi ed by video amplifi er and displayed

3RADAR and its Applications

using cathode-ray tube (CRT). The simplest form of Cathode-ray tube is plan position indicator (PPI),

which uses location of the target to map the polar co-ordinate in azimuth and range [2, 3, 4].Similarly

other forms of display are A-scope which uses rectangular co-ordinates to display amplitude vs range and

B-scope which display range vs angle. The most intriguing feature of RADAR is to uncover the range of

a target in accordance with the time taken by radiated signal to the target and back to the RADAR with

great accuracy and effi ciency. Figure 2 shows the Intensity modulation & defl ection modulation of target

obtained from RADAR [1].

Range

Angle

Amplitude

Range

Targets

Noise

() a() b

Figure 2: (a) intensity modulation from RADAR (b) defl ection modulation from RADAR

The RADAR range equation is climacteric in determining theRADAR range. It also describes the

RADAR characteristics and is very useful for designing RADAR system. The power Pr [1] returning to

the RADAR receiving antenna is given by the equation 1.

10 km 1 km 100 km 10 m 1 m 10 cm 1 cm 1 mm 0.1 mm

Wavelength

VLF LF MF HF VHF UHF SHF EHF

Very low

frequency

Low

frequency Medium

frequency

High

frequency

Very high

frequency

Ultra high

frequency

Super

high

frequency

Extremely

high

frequency

Myriometric

waves

Kilometric

waves

Hectrometric

waves

Decometric

waves

Metric

waves

Decimetric

waves

Centrimetric

waves

Millimetric

waves

Decimilli-

metric

waves

Band 4 Band 5 Band 6 Band 7 Band 8 Band 9 Band 10 Band 11 Band 12

Submilli-

meter For

infrared

Broadcast

band

OTH

rodar

Letter designations L S CXKuKa

Microwave region

Audio frequencies

Video frequencies

30 Hz 300 Hz 3 kHz 30 kHz 300 kHz 3 MHz 30 MHz 300 MHz 3 GHz 30 GHz 300 GHz 3,000 GHz

Frequency

Rodo frequencies

Figure 3: RADAR frequencies and electromagnetic spectrum

P

r = 2

11 112

22 3 4

PG A PG G

(4 R ) (4 ) R

er



= (1)

Where, σ = RADAR cross section (m2 )

= wavelength of a RADAR signal

4 Niraj Prasad Bhatta and M. GeethaPriya

G

1 = transmission antenna gain

G

2 = reception antenna gain

P

t = transmission power (W)

P

r = reception power (W)

A

er = effective aperture area of receive antenna

R = Range of RADAR

Usually, the range of RADAR is measured in Nautical mile.1Nautical mile is equal to 1.852Km.

In general, RADARs are operated in the range of frequencies extending from 220MHz to 35GHz. The

electromagnetic spectrum representing the range of conventional RADAR[5] is shown in fi gure 3. Earlier,

the letter codes such as S, C, L, X, etc. are used to profess the RADAR bands. The main purpose of

these letter codes is military secrecy. The table 1 shows the RADAR frequency letter based nomenclature

adopted by IEEE and their usage [5].

3. BASIC TYPES OF RADAR

There are basically two types of RADAR systems, namely:

( a) Primary RADAR : Another felicitous term used to describe Primary RADAR is Primary

surveillance RADAR (PSR). The transmitter radiates signal in all the direction, of which has

a minimum ratio proportion of energy signal gets refl ected back from the target to the receiver.

Several advantages of Primary RADAR are that it can operate independently of the target and

does not require any co-operation by the target under surveillance. It is used by military purpose

for detection of aircraft or ships. The disadvantages of Primary RADAR are; it needs high power

to be radiated from the transmitter to ensure the return of signal from the target. Since, only

minimum portion of signal get refl ected back to the receiver, refl ected signal may be disrupted by

noise and signal attenuation from various factors. It cannot provide lot of information about the

target, such as size and location with precise accuracy.

Table 1

Standard RADAR frequency nomenclature

Band Designation Frequency Range Usage

HF 3-30 MHz OTH surveillance

VHF 30-300 MHz Very-long-range surveillance

UHF 300-1,000 MHz Very-long-range surveillance

L 1-2 GHz Long-range surveillance

En route traffi c control

S 2-4 GHz Moderate-range surveillance

Terminal traffi c control Long-range weather

C 4-8 GHz Long-range Tracking Airborne weather detection

X 8-12 GHz Short Range tracking Missile guidance

Mapping, marine RADAR Airborne Intercept

Ka 12-18 GHz High Resolution Mapping

Satellite altimetry

K 18-24 GHz Little use (water Vapour)

Ka 27-40 GHz Very-High-Resolution Mapping

Airport surveillance

Millimeter 40-100 + GHz Experimental

5RADAR and its Applications

( b) Secondary RADAR : Secondary RADAR is also known as SSR (Secondary Surveillance

RADAR). This is alsocalled as Identifi cation Friend or Identifi cation Foe (IFF) system, means

that it can identify between friendly targets from the enemy target. Its working operation is based

on an active answering signal system. In addition to Primary RADAR, the SSR is also equipped

with the device called transponder in the target. SecondaryRADAR radiates a signal which is

received by a compatible transponder. After successful retrieving of the signal, the target sends

the useful information in the form of code. This information tells the receiver about the location,

altitude, status and many other useful information of the target. The advantages of SSR over PSR

are; the received signal is much more powerful and is not attenuated by any factors. The base

station can get proper information about the aircraft/ships. The disadvantages are that the base

station cannot get information from the aircraft that does not have any operating transponder and

from non-co-operative aircrafts. Hence, SSR is a dependent surveillance system.

4. CLASSIFICATION OF RADAR

There are many ways to classify RADAR. Based on functioning and major features, the RADAR can be

classifi ed as follows:

( a) General Pulse RADAR : This type of RADARradiates the repetitive seriesof short duration

rectangular pulses. There are two types of pulse RADARs. They are RADAR with Moving Target

Indication (MTI) andRADAR with Pulse Doppler. Both uses Doppler frequency shift that deals

with received signal to locate the target with moving motion. Example: Long range air surveillance

RADAR, weather RADAR, test range RADAR, etc.

• Moving Target Indication (MRI)RADAR: This type of RADAR can differentiate the

refl ected signals coming from the moving target & the stationary target and clutter by

observing Doppler shift in frequencies. It uses low pulse repetition frequency (PRF) to detect

the moving target in the clutter. Example: Ground based aircraft search and surveillance

RADAR systems.

• Pulse Doppler RADAR: This type of RADAR is similar to MRI RADAR. The only

difference is that it uses high or medium PRF to detect the moving target in the clutter. It is

used byarmy,navyand air force.

( b) Maximum Range Resolution RADAR: This type of RADAR uses short pulses in order to obtain

high resolution in the range, angle and doppler velocity co-ordinates. Stationary intruder in the

clutter can be detected using maximum range resolution. This type of RADAR is mostly used by

air force, navy and military.

( c) Pulse Compression RADAR: This type of RADAR is similar to high range resolution RADAR

which uses long pulse to get the resolution of a short pulse with the energy of along pulse. It uses

frequency or phase modulation of high energy long pulse to obtain the required resolution.

(d) CWRADAR : CWstands for continuous wave. It professes transmission and reception of

continuous sine wave at the same time. It employs Doppler frequency shift for detecting

moving tar gets. It is mostly used in vehicle speed detection [6]. Figure 4 shows a basic Continuous

RADAR [7].

( e) FM-CWRADAR : FM-CW stands for Frequency modulated continuous wave.This is a special

type of CW RADAR which uses frequency modulation to determine the range of the target. The

most common type of FM-CW RADAR is RADAR altimeter used in airplanes and satellite to

measure the altitude above the earth's surface.

(f) Synthetic Aperture RADAR (SAR) : It is a coherent imaging RADAR which is deployed in

aircrafts and satellite to get a high resolution RADARimage of a scene. It uses pulse compression

and primarily used by air force, navy, army and NASA.

6 Niraj Prasad Bhatta and M. GeethaPriya

Object

Original wave

Distance r

Sender/

Receiver

Reflected wave

Figure 4: Continuous wave RADAR

(g) Inverse Synthetic Aperture RADAR (ISAR) : ISAR is similar to that of SAR that uses high

resolution in range and Doppler frequency shift to obtain the cross range resolution. It can be used

to detect moving or stationary targets. It is primarily used by Air Force and NASA.

(h) Tracking RADAR : Tracking RADAR follows the trajectory of the target and predicts its

future positions. It continuously tracks the location of the target following its angle and range

information. The types of tracking RADARs are namely: Single Target Tracker (STT), Automatic

Detection and Tracking (ADT), Track while scan (TWS) and Phased array Tracker(PAT).

(i) Weather (meteorological) Observation RADAR : This type of RADAR measures the

precipitation rate, wind speedand other weather conditions and plays very important role in

meteorology studies.

(j) Imaging RADAR: This RADAR creates the 2-D image of the target. It is usually deployed in

satellites. RISAT (RADAR Imaging Satellite) is a series of Indian RADAR imaging reconnaissance

[8] satellites built by ISRO. They provide all-weather surveillance using synthetic aperture

RADARs (SAR).

(k) Military RADAR : Military RADAR system can be classifi ed as: land based, airborne and ship

borne RADAR.

• Land-Based Air Defense RADAR: This type of RADAR includes all the stationary and

mobile RADAR systems used in air defense.

• Missile Control RADAR: This includes tracking, fi re-control and weapons locating

RADAR systems.

• Naval and Coastal Surveillance and Navigation RADAR: This is a ship borne RADAR

used for surface and air tracking and surveillance.

• Airborne Surveillance RADAR: These are designed for early warning and tracking of

remotely piloted vehicles (RPV).

• Airborne Fire-Control RADAR: This RADAR system is used for weapon fi re control and

weapon guidance system.

5. APPLICATIONS OF RADAR

( a) Air Traffi c Control (ATC): RADARs are used for safety controlling of the air traffi c. It is used

in the vicinity of airports for guiding airplanes for proper landing in adverse weather conditions.

Usually, high resolution RADARis employed for this purpose. RADARs are used with ground

control approach (GCA) system for safe aircraft landing.

7RADAR and its Applications

(b) Aircraft Navigation : The weather avoidance RADARs and ground mapping RADARs are

employed in aircrafts to navigate it properly in all the conditions. Radio altimeter and Doppler

navigator are also a form of RADAR. These RADARs provide safety to aircraft from potential

collision with other aircraft and objects.

(c) Ship Navigation and Safety : High resolution Shore based RADARs are used for beaconing

and as an aid of navigation. During poor visibility due to bad weather conditions, the RADAR

provides safe travel by warning potential threats. They are also used to fi nd the depth of sea.

(d) Space: RADARs are used for docking and safely landing of spacecrafts. Satellite borne RADARs

are also used for remote sensing. Ground based RADARs are used to track and detect the satellites

and spacecraft.

(e) Remote sensing and Environment: They are employed in remote sensing for detecting weather

(meteorological) conditions of the atmosphere and tracking of planetary conditions.

(f) Law Enforcements : Highway police force widely uses RADARs to measure the vehicle speed

for safety regulations.

(g) Military area: RADARs have got wide application in military operations. They are used in air,

naval and ground for defense purposes. They are also used for tracking, surveillance and detection

of the target. Weapon control, Fire control and missile guidance is usually employed with various

types of RADARs [6]. Long range RADAR is very useful for many purposes. It is generally

used to track space objects. Furthermore, it is also used for ballistic missiles. Figure 5 shows a

Multipurpose RADAR system antenna that could serve variety of purposes such as broadcasting,

detection, etc.

Figure 5: Multipurpose RADAR Antenna

( h) Global Ozone Monitoring Experiment (GOME) Applications: Atmospheric available ozone

and No2 global monitoring have been going on after the invention of GOME Products (july 1996).

GOME products Can be used for retrieving other trace gases relevant to the ozone chemistry as

well as other atmospheric constituents. Furthermore, it can be used for climatic variable clouds,

solar index and aerosols. All these are crucial for assessing climate change.

(i) Microwave Sounder (MWR) Applications : In order to monitor the Antarctic ice cycle ERS-2

microwave sounder is being used. Mapping the radiometric properties of the ice-shelf, gives an

important input for the understanding of the dynamics, decay and growth of ice sheets. This this

is considered to be basic to the understanding of environmental and climatic changes.

(j) Wind Scatterometer (WSC) Applications: Wind scatterometers are used for accurate

measurements of the radar backscatter from the ocean surface when illuminated by a microwave

signal with a narrow spectral bandwidth to derive information on ocean surface wind velocity.

The amount of backscatter depends on two factors.. Dependent on wind stress which results in

wind speed at the surface, and wind direction are the two types of factors.

8 Niraj Prasad Bhatta and M. GeethaPriya

( k) Land use, Forestry and Agriculture : Observing the land surface is being considered as an

experimental application for ERS-1 data in the original mission targets. Major potential application

area for ERS data are being offered by the the ability to monitor crop development and forestry

changes independent of weather conditions.

(l) Other Applications : Ground penetrating RADARs are widely used by geologist for studying

the position of the earth for Earthquake detection. Scientists use RADAR for better study of

movements of animals,birds and insects. Archeologists use it for detecting buried artifacts. Many

industries and factories use it for safety purposes. During world war-2, Signal corps Radio-270

or Pearl Harbor RADAR was used by US army's as long-distance RADAR. It plays signifi cant

role in detecting the incoming raid, just before half an hour the attack has commenced and is most

useful [6].RADAR waves blaze an ample path for the rescue teams to search the needy people

during the earthquake [5] that detect the heartbeats through the fi nder search options of survivors

trapped in collapsed and damaged buildings after Nepal Earthquake of lately [9].Figure. 6show

the use of RADAR by rescue team during Nepal Earthquake onApril 25 2015.

Kathmandu

Central

Bharatpur

Figure 6: Use of RADAR by Rescue team during Nepal Earthquake on April 25 2015

Furthermore, if we consider fl oods which is the result of Bad weather therefore dense cloud ,

and thus optical sensors cannot be used for monitoring purposes. Radar satellites, however, can

penetrate the cloud cover with their microwaves, and thus deliver valuable information for future

planning and prevention.

6. CONCLUSION

It has been made known that there is a variety of applications for RADAR products. Additionally, ongoing

research and development is constantly increasing the existing range of applications. One of the most

important characteristics of RADARs is their capability to penetrate cloud cover and to obtain data

either by day or by night. It is this all-weather capability that has contributed extensively to the various

commercial applications of RADAR.

9RADAR and its Applications

7. REFERENCES

1. M. I. Skolnik, Introduction to RADAR Systems, New York: McGraw-Hill,2001.

2. Vilas s bagad,et al, Microwave and RADAR Engineering, 2008.

3. F. E. Nathanson, RADAR Design Principles, New York: McGraw-Hill, 1991.

4. Louis N. Ridenour. Radar System Engineering, volume 1 of MIT Radiation Laboratory Series. McGraw-Hill, New

York, 1947.

5. Panel on Frequency Allocations and Spectrum Protection for Scientifi c Uses, Handbook of Frequency Allocations

and Spectrum Protection for Scientifi c Uses, Washington, The National academic press, 2nd edition, 2015.

6. https://en.wikipedia.org/wiki/RADAR.

7. David Jenn, "Plasma Antennas: Survey of Techniques and Current State of the Art," NPS Technical Report NPS-

CRC-03-01, September 2003.

8. A. S. Kiran Kumar, "Signifi cance of RISAT-1 in ISRO's Earth Observation Programme" Current Science, Vol. 104,

No. 4, 25 February 2013.

9. http://www.digitaltrends.com/computin-g/new-satellite-images-shed-light-on-the-7-8-magnitude-nepal-earthquake/.

... RADAR was first used during the Second World War to find hostile aircraft and to direct anti-aircraft weapons. Today, RADAR is used for a variety of tasks such as surveillance systems, aircraft anti-collision systems, guided missile target locating system, meteorological monitoring, geological observations, automatic braking of vehicles, etc. RADAR transmits electromagnetic waves and registers the reflection of these waves from objects in the surrounding environment [1]. ...

... Today, RADAR systems extract a great deal of information from the reflected signal. As a result, RADAR has a broad span of applications; for instance, aircraft anti-collision systems, meteorological monitoring, geological observations, marine radars for ships, air-defense systems, guided missile target locating system, etc. [1]. Moreover, it is not only the reflected signal which is essential to analyze, but from the point of view of the object intercepting the RADAR wave, the incoming wave also needs to be analyzed to identify what type of RADAR emitted the wave. ...

The threat level (specifically in this thesis, for aircraft) in an environment can be determined by analyzing radar signals. This task is critical and has to be solved fast and with high accuracy. The received electromagnetic pulses have to be identified in order to classify a radar emitter. Usually, there are several emitters transmitting radar pulses at the same time in an environment. These pulses need to be sorted into groups, where each group contains pulses from the same emitter. This thesis aims to find a fast and accurate solution to sort the pulses in parallel. The selected approach analyzes batches of pulses in parallel to exploit the advantages of a multi-threaded Central Processing Unit (CPU) or a Graphics Processing Unit (GPU). Firstly, a suitable clustering algorithm had to be selected. Secondly, an optimal batch size had to be determined to achieve high clustering performance and to rapidly process the batches of pulses in parallel. A quantitative method based on experiments was used to measure clustering performance, execution time, system response, and parallelism as a function of batch sizes when using the selected clustering algorithm. The algorithm selected for clustering the data was Density-based Spatial Clustering of Applications with Noise (DBSCAN) because of its advantages, such as not having to specify the number of clusters in advance, its ability to find arbitrary shapes of a cluster in a data set, and its low time complexity. The evaluation showed that implementing parallel batch processing is possible while still achieving high clustering performance, compared to a sequential implementation that used the maximum likelihood method.An optimal batch size in terms of data points and cutoff time is hard to determine since the batch size is very dependent on the input data. Therefore, one batch size might not be optimal in terms of clustering performance and system response for all streams of data. A solution could be to determine optimal batch sizes in advance for different streams of data, then adapt a batch size depending on the stream of data. However, with a high level of parallelism, an additional delay is introduced that depends on the difference between the time it takes to collect data points into a batch and the time it takes to process the batch, thus the system will be slower to output its result for a given batch compared to a sequential system. For a time-critical system, a high level of parallelism might be unsuitable since it leads to slower response times.

... The development and modernization of radars that meet the demands of current surveillance systems [1][2][3][4] or the various applications in the civil field [5][6][7] such as meteorological control [8], requires the design and replacement of some of the Radar stages [1,9]. This need acquires a distinctive connotation in a country like Cuba, which has a large number of radars in service, and the call from institutions to substitute imports is extended. ...

  • Daryl Ortega Gonzalez Daryl Ortega Gonzalez

Current radars must meet the technological demands of today's world, which is why the modernization, replacement, or design of any of its parts is a strategic step. The antenna unit does not escape this reality. In it, it is usual to find several blocks among which are the power dividers, especially in radars that use antenna arrays and in particular air exploration radars such as the P18 and P12 use an unequal Wilkinson power divider with output to the two rows that are part of its antenna array. This paper proposes the design and simulation of an unequal Wilkinson power divider at the center frequency of 160 MHz of the Very High Frequency (VHF) band with a power ratio at the output ports of 60%-40%. The calculation of the components is carried out in Mathcad and the lumped circuit is simulated in AWR Microwave Office. From the results, Return Loss (RL) of-45.18 dB, isolation between the output ports of-49 dB, and power ratio at the output of S31 =-2.21 dB and S21=-3.98 dB in ports 3 and 2 respectively.

... • Military Radars have wide applications in military operations, and they could be classified as (1) land-based air defense radar, which includes all land-based radar systems used in air defense; (2) naval and coastal surveillance and navigation radar, which includes all shipborne radar used for surface and air tracking and surveillance; (3) airborne surveillance radar, which is used for detecting and tracking ground targets and aircraft in flight; and (4) missile and fire control radar, which is used for target tracking, fire control, and weapon guidance (Bhatta, 2017). ...

This paper presents an integrated model ofethical decision-making in marketing thatincorporates teleological, deontological andexistential theory. First, this frameworkprovides a descriptive model, which enables thedecision-maker to evaluate each step of thedecision-making process from three disparateperspectives in order to ensure a morecomprehensive ethical decision – that is, onewhich is good, right, and authentic. A set ofmoderating factors that influence the processand the outcome of the ethical decision-makingprocess is also identified. Second, we proposea pedagogical framework in developing a set ofmodules for a course curriculum on ethicaldecision-making in marketing. It has beenargued that the approaches to teachingmarketing ethics have traditionally been basedupon normative theories and that students ofmarketing ethics have been deprived of theopportunity to personalize their value systemsin ethical situations. Our proposed integratedframework allows for the student to applypersonal values to bear on the decision contextsince existentialism, at the core foundation,is really a theory of choice.

  • David Jenn David Jenn

Plasma antennas refer to a wide variety of antenna concepts that incorporate some use of an ionized medium. This study summarizes the basic theory behind the operation of plasma antennas based on a survey of patents and technical publications. Methods of exciting and confining plasmas are discussed, and the current state of the art in plasma technology is examined.

Microwave and RADAR Engineering

  • Vilas S Bagad

Vilas s bagad,et al, Microwave and RADAR Engineering, 2008.

Radar System Engineering, volume 1 of MIT Radiation Laboratory Series

  • Louis N Ridenour

Louis N. Ridenour. Radar System Engineering, volume 1 of MIT Radiation Laboratory Series. McGraw-Hill, New York, 1947.