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I've recently purchased and built the above Simultaneous RFID Tag Reader as a shield for a RedBoard.

At the moment, it's doing everything I hoped it would. However the range (without an external antenna) is a bit disappointing. At present, I'm struggling to get above 3 inches, even with the power set to 27.00. I've attached a couple of photos. Am I doing anything obviously wrong? Three inches seems a lot less than what I was promised (ba-dum ching).

Follow-up question: What sort of range could I expect, with only a small chance of being disappointed, if I fitted an external antenna? The project I'm working on requires a range of at least 4 feet. Should I start looking for another product?

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Hi Tom.

There are a lot of factors that influence range. We've been able to get up to 2 feet of range with the internal antenna, but I was once able to get 3' from the internal antenna, although I have not been able to reproduce that. 3-6" is typical though.

To maximize range, you need the tags way from any metal or conductive objects. (like your body) You also need the antenna away from conductive objects as well. I'm not sure what the radiation pattern for the onboard antenna looks like, but you will find that on certain orientations the range is better than others so it may take some experimenting to find where the range is the best.

You might try taping the tag to the end of a wooden yard stick and mounting the RFID reader on the end of a board so that the tags and reader are in as much free air as possible. By moving the tag in an imaginary sphere around the antenna, you should be able to map out where you get the best range.
Hi, Chris.

Thanks for getting back to me so quickly.

So 3-6 inches is typical without an external antenna. Good to know I'm not doing anything obviously silly - yet!

Would 4 feet, the range I require, be within the typical range *with* an external antenna?

Hi Tom.

When I try the reader at maximum power, with a 5 volt FTDI and our external antenna and I'm getting a 6 foot read range in the Universal Reader Assistant software.

If you plan on using the reader with an Arduino, you may need to power the reader with an external 5 volt power supply to get max range.
Forgive me for pestering you again.

I'm on the cusp of purchasing your "UHF RFID Antenna (TNC)", but I need a bit more information before I can justify said purchase to my boss.

What would the "directionality" be like with your external antenna? Is the sensitivity of the antenna very focused on one particular spot? What does its field of vision look like?

Is it possible to give the Simultaneous RFID Tag Reader "chameleon eyes" by hooking it up to multiple antennae? If so, would this diminish the range with respect to one of those antennae?

Hi Tom.

Sadly we don't have much of a data sheet for the antenna we carry so I don't have a diagram with the radiation pattern on the antenna. I can say from experimentation that the antenna is most sensitive directly in front with sensitivity dropping as you go off center from the antenna. If you picture a cone projecting outward from the antenna, that would describe what I'm talking about.

The area immediately behind the antenna also appears to radiate a signal, but it's very weak and you need a tag within a few inches of the back of the antenna.

Although the M6E module on the board has the capability of switching between up to 16 different antennas, sadly the circuitry needed to do that isn't included on the shield and our library doesn't support more than one antenna.