ThingMagic M6e User Guide
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Support for Return Loss Measurement
The firmware estimates the return loss of individual antenna ports, based on multiple readings at multiple
channels within the active region. (For the North American region, with 50 channels, this measurement can
take as long as 600 msec). The return loss value can be obtained through the API by getting the “/reader/
antenna/returnloss” parameter value as well as by using the “CmdGetAntennaReturnLoss” method. The
sample code “ReaderStats” illustrates the recommended method for obtaining this information. The values
returned will look like this:
Antenna Return Loss
Antenna 1 | 30
Antenna 2 | 4
Which indicates a return loss of 30 dB for antenna 1, and 4 dB for antenna 2.
This measurement loses accuracy as the numbers increase due to the impact of internal signal reflections
that increasingly obscure the measurement of the small signal reflected only at the antenna.
The return loss is measured at an RF level of +15 dB to limit impact to other services that are running in the
same region while the return loss measurement is being made.
NOTE: The M6e uses a small amount of DC current to detect antennas. Use of this method to determine
if an antenna is present and of the return loss to determine if the antenna is tuned to the correct
frequency is the best way of ensuring maximum performance for the channel of operation.
Protocol Support
The M6e has the ability to support many different tag protocols. Using the MercuryAPI ReadPlan classes
the M6e can be configured to single or multi-protocol Read operations. The current protocols supported are
(some may require a license to enable):
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