# JED - October 2017 - 46

```EW 101

Space EW - Part 17

EW Operations from Space

cont'd.

JAMMING A GROUND-BASED RADAR FROM SPACE
In the last two columns, we dealt with the jamming of
ground based communication systems from space. The problems discussed dealt with tactical communication at UHF with
relatively low antennas. The propagation mode appropriate
to the jammed communications was "2 RAY," which is quite
"lossey," so the satellite jammer could do a relatively good job
when it was above the horizon. Now we will consider radar
threats, which are at microwave frequencies and propagate
"line-of-sight."

meters. 1 MW is 90 dBm. The antenna boresight gain is found
from the formula:
G =-42.2 + 20 log D + 20 logF
Where: G is the boresight gain of the antenna in dB
D is the diameter of the antenna in meters
F is the operating frequency in MHz
The gain of the radar antenna is calculated to be:

The Journal of Electronic Defense | October 2017

46

G = -42.2 + 9.5 + 74 = 41.3 dB
The distance from the satellite to the radar being jammed
depends on the location of the jamming satellite, the jammed
Let's assume that the average side lobes of the radar's anradar, and the radar's target. For convenience, we will assume
tenna are 20 dB below the main-beam boresight gain. Thus, the
that the jamming satellite orbit and the satellite's location in
side-lobe gain is assumed to be 21.3 dB.
that orbit are the same as they were for last month's problem
with communication jamming, as shown in Figure 1. It is a
circular orbit at 300 km altitude with an inclination of 60
ERP = Tube power (in dBm) + Boresight gain in dB = 90 dBm +
degrees. The radar we are jamming is located on the Earth
41.3 dB = 131.3 dBm
at 35 degrees North Latitude and 105
degrees East Longitude. The period of
Distance
the satellite is 90.364 minutes. This is
Longitude
from
North
determined from the formula presented
satellite
Pole
in the June 2016 "EW 101" column. In
the August 2017 column, we calculated
that the time the jammer is over the
location
horizon to the radar it is jamming (if it
Latitude
passes directly over the target) will be
19.3 minutes.
Placing the satellite where it was
last month (sub-vehicle point at 30°
North Latitude and 100° East LongiSub-vehicle
tude), we have calculated the distance
point
from the satellite to the jammed radar
to be 828 km.

THE JAMMED RADAR AND ITS TARGET
Now, consider the radar we are attempting to jam. We will set the radar's
frequency at 5 GHz, its tube power at 1
MW and its antenna diameter at 3

Latitude
of sub-vehicle
point

Center
of Earth

Figure 1: The propagation distance from the satellite to the target radar depends on the orbital
geometry.

continued on page 67
Figure 1: The propagation distance from the satellite to the target radar
depends on the orbital geometry.

```

The View From Here
Conferences Calendar
Courses Calendar
From the President
The Monitor
Washington Report
World Report
Maximizing EW Capabilities Within the Brigade Combat Team
Homing Senses: Anti-Ship Seekers Show New Diversity
The Heat is On
EW 101
2018 EW/SIGINT Resource Guide
AOC News
JED Quick Look
JED - October 2017 - intro
JED - October 2017 - cover1
JED - October 2017 - cover2
JED - October 2017 - 3
JED - October 2017 - 4
JED - October 2017 - 5
JED - October 2017 - The View From Here
JED - October 2017 - 7
JED - October 2017 - Conferences Calendar
JED - October 2017 - 9
JED - October 2017 - Courses Calendar
JED - October 2017 - 11
JED - October 2017 - From the President
JED - October 2017 - 13
JED - October 2017 - 14
JED - October 2017 - insert1
JED - October 2017 - insert2
JED - October 2017 - The Monitor
JED - October 2017 - 16
JED - October 2017 - 17
JED - October 2017 - 18
JED - October 2017 - 19
JED - October 2017 - 20
JED - October 2017 - 21
JED - October 2017 - Washington Report
JED - October 2017 - 23
JED - October 2017 - World Report
JED - October 2017 - 25
JED - October 2017 - Maximizing EW Capabilities Within the Brigade Combat Team
JED - October 2017 - 27
JED - October 2017 - 28
JED - October 2017 - 29
JED - October 2017 - 30
JED - October 2017 - 31
JED - October 2017 - 32
JED - October 2017 - 33
JED - October 2017 - 34
JED - October 2017 - 35
JED - October 2017 - Homing Senses: Anti-Ship Seekers Show New Diversity
JED - October 2017 - 37
JED - October 2017 - 38
JED - October 2017 - 39
JED - October 2017 - 40
JED - October 2017 - 41
JED - October 2017 - 42
JED - October 2017 - 43
JED - October 2017 - The Heat is On
JED - October 2017 - 45
JED - October 2017 - EW 101
JED - October 2017 - 47
JED - October 2017 - 48
JED - October 2017 - 49
JED - October 2017 - 50
JED - October 2017 - Technology Survey: COMINT/DF Receivers
JED - October 2017 - 52
JED - October 2017 - 53
JED - October 2017 - 54
JED - October 2017 - 55
JED - October 2017 - 56
JED - October 2017 - 57
JED - October 2017 - 58
JED - October 2017 - 59
JED - October 2017 - 60
JED - October 2017 - 61
JED - October 2017 - 62
JED - October 2017 - 63
JED - October 2017 - 64
JED - October 2017 - 65
JED - October 2017 - 66
JED - October 2017 - 67
JED - October 2017 - 2018 EW/SIGINT Resource Guide
JED - October 2017 - 69
JED - October 2017 - 70
JED - October 2017 - 71
JED - October 2017 - 72
JED - October 2017 - 73
JED - October 2017 - 74
JED - October 2017 - 75
JED - October 2017 - 76
JED - October 2017 - 77
JED - October 2017 - 78
JED - October 2017 - 79
JED - October 2017 - 80
JED - October 2017 - 81
JED - October 2017 - 82
JED - October 2017 - 83
JED - October 2017 - 84
JED - October 2017 - 85
JED - October 2017 - 86
JED - October 2017 - 87
JED - October 2017 - 88
JED - October 2017 - 89
JED - October 2017 - AOC News
JED - October 2017 - 91
JED - October 2017 - 92
JED - October 2017 - Index of Advertisers
JED - October 2017 - JED Quick Look
JED - October 2017 - cover3
JED - October 2017 - cover4
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