ANTCALC - Radar Antenna Calculator


A question which comes up quite often in discussions amongst radar users is: “How does a particular radar antenna perform”? The Radar Antenna Calculator provided on this page helps to find answers. For the most basic antenna parameter, the aperture width, the calculator computes the horizontal beamwidth of the antenna’s main lobe. This figure determines the azimuthal resolution of the radar system. If the vertical beamwidth is known or assumed, e.g. using the default value, the antenna gain will be calculated. This parameter determines the range performance. Furthermore, the far-field distance is computed, i.e. the distance at which the antenna main lobe is almost completely built up and the antenna can be used for precision measurement. The calculator applies the equations described in the document ’blanket_mcd.pdf’. These equations are applicable for ‘slotted wave guide antennas’ with a cos² aperture distribution, but  work sufficiently well for other antennas also, as can be tested with the data from the table below.



AntCalc shown below is made available on this web site for educational and scientific purposes and under exclusion of any form of warranty, what so ever. The author reserves the full copyright. Any form of commercial use requires a license by the author. If you accept these conditions, you may use AntCalc now.  Please make sure that Java is enabled in your browser. 





The following table shows some data representative for radar antennas used aboard ships or ashore. You can test the calculator with these data. Please be aware that deviations between the data in the table and the results from the calculator are to be expected, as the real antenna aperture is not identical with the outer dimensions often stated by manufacturers, and that the calculation represent approximations only. The results should be good enough for practical use, though.



Classification

AW (ft)

AW (mm)

hBeamWidth

vBeamWidth

Gain (dB)

SWGX1.6,H,F

5

1678

1,5

23

28

SWGX2.5,H,F

8

2578

0,9

21

31

SWGX3.6,H,F

12

3600

0,6

19

33

SWGX6.7,H,F

22

6770

0,4

15

36

SWGX7.3,C,I

24

7300

0,35

17

35

 

 

 

 

 

 

PRFX5.5,VHC,I

18

5500

0,45

4,2

39

PRFX7.5,VHC,I

24

7500

0,33

2,4

44,5

PRFX7.5,VHC,P

24

7500

0,33

1,8

46

 

 

 

 

 

 

SWGS2.7,H,F

9

2700

2,8

27

25

SWGS3.5,H,F

12

3500

2

27

26

SWGS4.2,H,F

14

4220

1,8

20

28


The author’s antenna classification used in the table above:
SWG := slotted wave guide
PRF : = parabolic reflector antenna
X,S := Xband or S band
x.x := aperture width in m
V,H,C stands for vertical, horizontal and circular polarisation.


 

 

 


Ingo Harre, Bremen, Germany, Content last modified on 2009/04/14