antenna connected to coupler
i have connected two antenna to my hybrid coupelr
one of the port is terminated and the other is the input
im thinking how would i measure s21 or s31....forward transmissions.....
i can measure s41 the isolation and s11 the input reflection but how the forward transmisson
transmittion line and each coupler has loss this is first
one port is terminated so half load -1/3rd
is expected loss + transmition loss
rest is foward power from that impedance point
? what do you think now?
well i know the what you are talking about but im saying how will i measure the complete system
if coupler and antennas get fabricated on pcb board . i cannot measure them separatly once they get fabricated together
so what? why do you want to know it actually? It's the overall antenna performance that counts. You can measure it.
Or try to cut the PCB traces or determine the coupler behaviour in a simulation. But the connected antenna's input impedance is most likely unknown as well.
actually i matched the antenna to 50 ohm and then matched the coupler to 50 ohm as well but as i told u when u combine them the two ports of the coupler are occupied by the antenna. so we are left with only s11 and s14. port 2 and port 3 are connected to the antenna.
i cannot even figure it in simulation that how to measure s21 and s31....because there are no ports at 3 and 4....there are antennas....
so its seem complicated to measure the forward transmissions.
i want to measure the forward transmission because it will tell me the input power to the antennas and i can measure the effeciency
You said that you matched the antenna to 50 ohms, and also you matched the coupler to 50 ohms. That means all ports have 50 ohms (faithfully).
Anyway, just measuring the conducted forward power into the antenna doesn't tell you too many things about radiated efficiency (even if you don't have too much reflected power).