Any idea how to proceed with this , rf antenna ,IC (any Freq range), oscillator etc to be used in order to interface with pic microcontroller or any other microcontroller
You have a lot of choices, and it seems like standard wireless protocols (BLE, Zigbee) and LoRa wireless transceivers would work but are probably overkill. If you use one of these solutions you probably want a module, saving yourself a PCB design exercise involving oscillator, antenna and related signal integrity issues.
You might look at NFC/RFID tag and reader devices, I've never designed with them but suspect they could be used to solve your problem. I have no idea how small the RFID reader antenna can be made, and it may involve more PCB real estate (and power?) than a BLE/Zigbee or LoRa antenna.
Defining a min/max detection range (eg. 1 meter always detected, 2 meters never detected) may be tricky. Perhaps the NFC/RFID antenna size and power will influence detection range, which could work to your advantage. In any of these approaches, if you want the detection to work very quickly you will have to broadcast/poll more frequently which will involve more power. Good luck!
Thank you matthewbarr.
Let me explain the way I designed.
I used 433 mhz rf transmitter and receiver module(cheap modules available in shopping sites like Amazon) interfaced both 433 mhz transmitter and receiver with pic16f877a microcontroller, since I don't want the transmitter and receiver to be powered up in same circuit because the device identifies itself when both are switched on in the same device, so I controlled the switching using microcontroller like the way so that when transmitter is switched on, receiver will be turned off, vice versa,this idea was seems to be good ,but when I practically implemented and tested them ,it was not efficient ,there was only 50% chance of picking the signal/identify the device.
In order to make it cost efficient I approached this , let me try it in your suggested way, so that there won't be any PCB design that I should concentrate about.
Oh, from your original post I didn't realize you were this far along, the slow reveal!
What you have done makes sense, and you might want to spend some time debugging and getting to the root cause of it not working reliably.
The protocol-based solutions (BLE, Zigbee and similar) usually come with an embedded processor such as an ARM. The vendor will typically supply demo projects and a software development kit, you then have a programming effort to develop an application that meets your needs. If protocol and hardware are new to you, this is not nearly so easy as using a basic wireless transceiver with a relatively simple command and control interface.
Yes exactly and i should work on modules like zigbee to achieve efficient output, before that I will give a thought abt to try debug what is going wrong with my existing design
Thank you Matthewbarr
This is not aimed to help, but I couldn't resist the temptation to say that, in the eighties ( yes, I'm old ), British magazine Elektor Electronics published a pair of circuits doing exactly that. They were called 'forget me not transmitter' and 'forget me not receiver' and were aimed to help a person not forget his/her umbrella when finished visiting someplace on a rainy day. :-)
Thank you for letting me know