Below, you see the only schematic of a 6 pages-datasheet of an UHF RFID module (working frequency = 840…930 MHz):
There are three questions:
- What is that ANT-MMCX? I search it in Google and I found two components named ANT-GPS-MMCX and ANT-GSMQB-MMCX-ND. Which one is appropriate for this module?
- The antenna is connected to the module with a 50Ω microstripe line. The question is "What is this microstripe line?". I must design and build it myself or there are created ones in the stores? What happens if I connect the antenna to the module with a simple wire?
- Will the above circuit works properly if I use a 5V mobile phone charger as the power supply (let assume it can provide the require current) and connect RXD and TXD to my computer's serial port and also put all the circuit on a simple bread board? or there are a lot of points in high frequency communication circuits that I must consider and apply to the board design that are not shown in the image? (If so, let me know the most important ones).
Best Answer
ANT-MMCX means Antenna MMCX connector. It depends on your antenna, but basically its just a matched connector.
A Microstrip line is a transmission lines structure which is easy to build on a pcb. It consists of a trace over a reference plane with a set width and distance to produce 50 ohm impedance. You can find plenty of calculators online to calculate the width and distance from the reference plane for you. If you connect the antenna with a simple wire you can expect an impedance mismatch and very bad performance to the point of being impossible to receive the signals. You cannot build this on a breadboard, you need a proper pcb.
I would suggest you buy a complete module, this way you could probably use it on a breadboard.
EDIT:
From looking at this datasheet it seems like this module is meant to be soldered on a pcb, how did you plan to use it on a breadboard ? you might be able to solder some sort of a 50ohm coax directly to the module and connect it to an antenna.