Intermodulation Products Calculator

Calculator Inputs

Tone 1 frequency

Tone 2 frequency

Frequency unit

Band minimum

Band maximum

Maximum order

Carrier power per tone (dBm)

System gain (dB)

OIP3 for IM3 estimate (dBm)

Displayed decimal places

Sort results by

Options

Include difference products

Include even-order products

Keep products that overlap carriers

Example Data Table

Sample RF planning case

Tone 1	Tone 2	Band	Max order	Carrier power	Gain	OIP3
900 MHz	905 MHz	890 to 915 MHz	5	0 dBm	15 dB	35 dBm
1805 MHz	1810 MHz	1800 to 1820 MHz	7	-5 dBm	12 dB	32 dBm
2.400 GHz	2.405 GHz	2.390 to 2.490 GHz	5	-10 dBm	20 dB	38 dBm

Formula Used

The calculator forms spur frequencies from two input tones using:

f_IMD = |m × f₁ ± n × f₂|

Here, m and n are non-negative integers. The product order is:

Order = m + n

When you supply carrier power, gain, and OIP3, third-order product level is estimated with:

P_IM3,out ≈ 3 × P_out − 2 × OIP3

Where P_out = Carrier Power + Gain. This estimate is most useful for equal two-tone testing and quick RF screening.

How to Use This Calculator

Enter the two interfering tone frequencies in your chosen unit.
Set the band limits that define your protected or observed RF range.
Select the highest product order you want listed.
Enable difference and even-order products when your design requires them.
Enter carrier power, gain, and OIP3 if you want IM3 level estimates.
Press the calculate button to show the summary and detailed spur table above the form.
Use the CSV or PDF buttons to export the current result set.

Frequently Asked Questions

1. What does this calculator actually list?

It lists fundamental tones and generated intermodulation products from two frequencies. Each row shows order, equation, resulting frequency, band position, and estimated IM3 level when available.

2. Why are third-order products important?

Third-order products often land close to wanted channels. They are common troublemakers in receivers, transmit chains, shared sites, and amplifier linearity testing.

3. What is the benefit of the band filter?

The band range highlights whether a spur falls inside your channel plan or protected span. That makes screening much faster during design, troubleshooting, or compliance review.

4. Should I include even-order products?

Include them when mixers, imperfect balance, or certain nonlinear paths matter. Leave them off for a faster odd-order review when you only need classic RF intermod screening.

5. How is the IM3 level estimate used?

It gives a quick third-order output estimate from carrier power, gain, and OIP3. Treat it as a planning approximation, not a substitute for lab verification.

6. Can I use units other than MHz?

Yes. You can enter frequencies in Hz, kHz, MHz, or GHz. The calculator normalizes values internally and reports results in MHz for comparison.

7. Why do some products repeat near carriers?

Some combinations collapse onto carrier frequencies or identical spur locations. Use the overlap option when you want to keep those matches visible for deeper analysis.