The Radar Equation Calculator app is a
tool for solving the basic radar equation for monostatic or bistatic
radar systems. The radar equation relates target range, transmitted
power and received signal SNR. Using this app, you can solve for any
one of these three quantities. If you know the transmit power of your
radar and the desired received SNR, you can solve for the maximum
target range. If you know the target range and desired received SNR,
you can compute how much power you need to transmit. Finally, if you
know the range and transmit power, you can calculate the received
SNR value.

After you choose the type of solution, set other parameters
to build a complete model. The principal parameters to specify are
target cross-section, wavelength, antenna gains, noise temperature,
and overall system losses.

Compute the maximum detection range of a 10 GHz, 1 kW, monostatic
radar with a 40 dB antenna gain and a detection threshold of 10 dB.
From the Calculation Type drop-down list, choose Target
Range as the solution and choose Configuration as monostatic.
Enter 40 dB for the antenna Gain, and set the Wavelength to
3 cm. Set the SNR detection threshold parameter
to 10 dB. Assuming the target is a large airplane, set the Target
Radar Cross Section value to 100 m^{2}.
Next, specify the Peak Transmit Power as 1 kW
and the Pulse Width as 2 µs. Finally, assume
a total of 5 dB System Losses.

Continue with the results from the previous example. Use multiple
pulses to reduce the transmitted power while maintaining the same
maximum target range. Clicking on the arrows to the right of the SNR label
opens the Detection Specifications for SNR menu.
There, set the Probability of Detection to 0.95,
the Probability of False Alarm to 10^{–6},
and the Number of Pulses to 4. Then, reduce the Peak
Transmit Power to 0.75 kW. Assume a nonfluctuating target
model, i.e., the Swerling Case Number is 0.

The maximum detection range is approximately the same as in
the previous example, but the transmitted power is reduced by 25%.

Solve for the geometric mean range of a target for a bistatic
radar system. Specify the Calculation Type as Target
Range and Configuration as bistatic.
Next, provide a Transmitter Gain and a Receiver
Gain parameter, instead of the single gain needed in the
monostatic case.

Alternatively, to achieve a particular
probability of detection and probability of false alarm, open the Detection
Specifications for SNR menu. Enter values for Probability
of Detection and Probability of False Alarm, Number
of Pulses, and Swerling Case Number.

Compute the required peak transmit power of a 10 GHz, bistatic
X-band radar for a 80 km total bistatic range, and 10 dB received
SNR. The system has a 40 dB transmitter gain and a 20 dB receiver
gain. The required receiver SNR is 10 dB. From the Calculation
Type drop-down list, choose Peak Transmit Power as
the solution type and choose Configuration as bistatic.
From the system specifications, set Transmitter Gain to
40 dB and Receiver Gain to 20 dB. Set the SNR detection
threshold to 10 dB and the Wavelength to 0.3
m. Assume the target is a fighter aircraft having a Target
Radar Cross Section value of 2 m^{2}.
Choose Range from Transmitter as 50 km, and Range
from Receiver as 30 km. Finally, set the Pulse
Width to 2 µs and the System Losses to
0 dB.

Compute the received SNR for a monostatic radar with 1 kW peak
transmit power with a target at a range of 2 km. Assume a 2 GHz radar
frequency and 20 dB antenna gain. From the Calculation Type drop-down
list, choose SNR as the solution type and set
the Configuration as monostatic.
Set the Gain to 20, the Peak Transmit
Power to 1 kW, and the Target Range to
2000 m. Set the Wavelength to 15 cm.

Find the received SNR of a small boat having a Target
Radar Cross Section value of 0.5 m^{2}.
The Pulse Width is 1 µs and System
Losses are 0 dB.