Controlled Reception Pattern Antenna (CRPA): How It Stops GPS Jamming
A controlled reception pattern antenna, or CRPA antenna, uses an array of elements to place deep nulls toward jammers while still receiving the satellites. Here is how it works, what N elements buy you, and how to choose one.
What is a controlled reception pattern antenna?
A controlled reception pattern antenna (CRPA antenna) is a GNSS antenna made of several elements whose signals are combined electronically. Instead of hearing the whole sky equally, like a standard patch antenna, a CRPA antenna shapes its reception pattern in real time: it keeps gain toward the satellites and drives gain toward a jammer down to almost nothing.
That is the whole idea. GNSS signals reach the ground at roughly −130 dBm, below the thermal noise floor, so a transmitter of a few watts nearby can bury them. A CRPA antenna does not try to out-shout the jammer; it stops listening in the jammer's direction.
How a CRPA antenna places a null
Each element of the array sees the same jammer at a slightly different time, because it sits at a slightly different place. The anti-jamming module measures those differences and weights each element so that, when the outputs are added, the jammer's energy cancels. The result is a deep notch in the antenna pattern — a null — pointing at the interference source.
Satellites survive the same operation because they are spread across the sky and arrive from many directions at once. Cancelling one bearing removes the jammer and costs very little satellite signal. When the jammer or the platform moves, the weights are recomputed continuously, so the null follows it.
Why the number of elements matters
An array of N elements can place at most N−1 independent nulls. That is geometry, not firmware, and it sets how many separate jammers a CRPA antenna can suppress at the same time. A 4-element CRPA antenna handles up to 3 jammers, a 7-element up to 6, an 8-element up to 7 and a 16-element up to 15.
More elements also means a larger aperture, more weight and more power. That trade-off is covered in detail in how many CRPA elements you need.
| Elements | Max jammers | infoX example | Weight | Suppression, 1 jammer |
|---|---|---|---|---|
| 4 | 3 | TX-S65-4CH-SNB | ≤130 g | ≥95 dBc |
| 7 | 6 | TX2504-3T7A21C-WG-DT | ≤1200 g | ≥120 dBc |
| 8 | 7 | TX-8AT-FULL-KGR-34V | ≤720 g | ≥110 dBc |
| 16 | 15 | TX2511-16A-SNB | ≤1250 g | ≥100 dBc |
CRPA antenna vs a standard GPS antenna
A standard GPS antenna, sometimes called a fixed reception pattern antenna (FRPA), has one pattern that never changes. It cannot tell a satellite from a jammer, so once the jammer is stronger than the satellites, the receiver loses lock.
A CRPA antenna keeps the receiver working through that same interference. The cost is size, weight, power and price, which is why CRPA antennas are chosen for platforms where losing navigation is not acceptable: UAVs, eVTOL, unmanned ground vehicles, and timing and reference stations.
Does a CRPA antenna stop spoofing too?
A spoofer is also a transmitter at one location, so its counterfeit constellation arrives from one bearing — unlike real satellites. An array that can read direction can therefore suppress a spoofer as well. In the infoX range, TX2501-AJS-4CH-DPA and TX2512-AJS-16CH-DPA add anti-spoofing, holding residual spoofing signal to ≤20 dB C/N₀. More in how anti-spoofing works.
How to choose a CRPA antenna
Start with the platform, not the datasheet: payload weight, available power and mounting space rule out most options before interference does. Then match the element count to the number of jammers you expect, check the constellations and bands you need, and decide whether you need anti-spoofing.
All eight infoX models are compared side by side in our CRPA antenna range. If you are unsure, send us your platform and we will name the model.