# RF - separate transmitter and receiver antennas for half duplex

i was wondering why is it for just half duplex systems, don't we have a dedicated transceiver and a dedicated transmitter antenna.

ok, just hear me out...

assuming we are using grounded monopoles, we can have a resonator connected to a diode whose anode is connected to the transmitting antenna, and have a receiving second antenna connected to the cathode of another diode then going to the resonator.

the transmitting and receiving antennas would also be made of different materials that are nonreciprocal. ferrites that are biased to transmitting and receiving (higher gains).

since they're half duplex, we don't even have to have 2 different resonator circuits. so basically, if this is feasible, we don't have to change anything in the current systems, just plug in these dedicated antennas...

am i wrong here??

EDIT 1:

was:

RF - separate transmitter and transceiver antennas for half duplex

i was wondering why is it for just half duplex systems, don't we have a dedicated transceiver and a dedicated transmitter antenna.

now:

RF - separate transmitter and receiver antennas for half duplex

i was wondering why is it for just half duplex systems, don't we have a dedicated receiver and a dedicated transmitter antenna.

"transmitter and receiver"... that's what an amateur gets for going into subjects he doesn't know enough of....

EDIT 2:

also, i've always intended to use a ferrite rod antenna for the monopole. i was very disappointed that i couldn't, as there are no ferrites that can operate in the GHz. as what i meant above that this, if it even works, is a simple plug-in.

• I am struggling to understand what point you are trying to make here. – Andy aka Jan 14 '15 at 9:29
• You're not even wrong. – EM Fields Jan 14 '15 at 9:39
• @andy: coz i'll be putting together said antenna... and i want to know i'm not barking up the wrong tree. – Dehbop Jan 14 '15 at 9:40
• "dedicated transceiver antenna"? – Andy aka Jan 14 '15 at 9:45
• "i was wondering why is it for just half duplex systems, don't we have a dedicated transceiver and a dedicated transmitter antenna." $\$ A transmitter AND a transceiver??? – EM Fields Jan 14 '15 at 10:03

Half duplex means transmit, switch and listen - this means one common antenna can be used and one common transmit/receive frequency (if required). If you have separate transmit and receive antennas then half duplex is still possible (without a T/R switch) but you have to ensure you do not damage the receiver input circuit when transmitting.

However, for half duplex I don't see the point (if tx and rx frequencies are very similar).

Regards "resonator connected to a diode whose anode is connected to the transmitting antenna, and have a receiving second antenna connected to the cathode of another diode then going to the resonator." - are you trying to postulate some kind of filter that prevents some of the transmit power entering the receiver antenna input?

If so then this is also OK - this is how analogue cell-phones used to work as I remember and they could simultaneously transmit whilst receiving (again from memory).

• yes, you're correct about using 2 simple diode to filter the input and output... well... does it work?? i was simply assuming that inrush of electrons and the opposite is what generates the radio waves (either current or voltage differential, i don't know). if it didn't, i was ready to look for an appropriate filter. – Dehbop Jan 14 '15 at 11:45
• I can't say whether it works because I'd need a circuit diagram. – Andy aka Jan 14 '15 at 12:01
• "resonator connected to a diode whose anode is connected to the transmitting antenna, and have a receiving second antenna connected to the cathode of another diode then going to the resonator." i just checked some circuit designs and it seems that for receiving antennas, the a diode's cathode should be connected to the receiving antenna, then to the resonator... for the transmitter antenna, i still don't know how to bias the diode, if a single diode works at all. – Dehbop Jan 15 '15 at 11:55
• i thought the cathode of the diode needs to be connected to the antenna for receiving as i simply assumed the photons from radio waves knocks out electrons from the antenna material. – Dehbop Jan 15 '15 at 12:00
• No circuit no comment dude. – Andy aka Jan 15 '15 at 12:06