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Near field H-Loop antenna for RF / EMI / EMC diagnosis

We have been adding more and more specific antennas to our offering over the last few months, in order to help users get the best value from RF Explorer.

As you probably know, the right antenna at the right place makes all the difference. Directional, omnidirectional, narrow band, wide band, patch, cloverleaf are available for different frequency ranges at SeeedStudio and other distributors.

But all our available antennas so far are used to measure the so called "far field" transmissions. They are fine to measure and diagnose all sort of RF transmissions which are a few wavelengths away. But for a number of tasks, most notably sniffing and measuring components or cables in a PCB or electronic device, far field antennas are not good because lack enough resolution to determine with precision where the transmission comes from. Furthermore, a far field antenna will keep receiving RF radiations from all sort of external, distant sources and mixing the result with the nearby radiation being diagnosed.

To assist on that, RF guys use "near field" antennas. They offer way more resolution for close-by diagnosis, and are mostly unaffected by far field transmission. Unfortunately, most near field antennas cost several times more than RF Explorer device itself; They are used for very specific tasks and not sold in the mass market. So most cost-sensitive setups would not have access to near field antenna... or that was the story until now.


We are happy to introduce our first custom designed, fully calibrated, near field antenna at the right price. This first model is called RFEAN25 and is a very sensitive, compact and easy to use H-loop near field antenna. We fine-tuned prototypes and experimented ideas for more than 15 months. Thanks to this creative design, our lab testing show RFEAN25 is at least 10dB more sensitive in the range 20-6000MHz than other H-loop options in the market, at a much lower cost.

If you compare it with other near field competing antennas, you will see RFEAN25 is smaller and lighter, exactly what you need when space is constrained in a PCB.

We added a high quality semi-flexible RF cable which works as the handler of the antenna. The big advantage of this approach: you can shape the cable the way you want for the antenna to be located exactly where you need, in most cases with no need to keep it on your hand.

It is the ideal antenna for the tasks listed below:

  • Detect radiation: Easily determine the electronic component or PCB signal track creating a wanted or unwanted RF radiation.
  • Sniff and measure: Follow signal path in any RF or high speed digital circuit, with no need to actually contact the circuit itself.
  • Find bugs: Thanks to great spatial resolution, it is ideal antenna to check for RF bugs such as hidden cameras or microphones in a room.
  • Diagnose EMI: Check any electronic device for RF radiation limits. This may include a connector with leakage, a module creating interference in a drone or RC plane, an oscillator or crystal that may not be working at the right frequency, etc
  • Pre-compliance EMC testing: Help on finding possible sources of interference in a design before passing an expensive EMC lab test for approval EU / FCC.
  • Create interference: it can be used to introduce RF interference in specific areas of a circuit or device, to check on side effects as well as diagnose root cause of intermittent problems. Connect it to a Signal Generator and use CW or Frequency Sweep to check how your circuit respond.
  • RFEAN25 can be used with RF Explorer Spectrum Analyzer and Signal Generator. But it can be used with any spectrum analyzer brand, as well as oscilloscopes. It is DC decoupled up to 25V so pretty much risk free if makes contact with the PCB circuit under test.


 The RFEAN25 is available for preorder at 15% discount till mid-October, for only $23.

You will not find near field antennas at this price tag anywhere. Use Seeedstudio link here.

Other near field antennas will be available later this year, as a full 4-antenna kit with 3 popular H-Loop sizes and one E-Field size. But we will keep RFEAN25 as separated antenna option as this is the best multi-task near field antenna most users need. More demanding users may go to the full antenna kit, it will be available at a very reasonable price tag.