FvM said:It rather looks like two "printed" inductors (for the respective one-transistor oscillators) than "antennas". Because we
don't know the purpose of the board, we hardly can guess, why there are two of them.
If it's a transmitter, it obviously hasn't been designed to achieve a range. You surely can't change the loop size, and most
likely not add a whip antenna without threatening the intended operation. You have to modify the oscillator circuit or add
output stages.
An obvious reason to limit the transmitter range is compliance with legal regulations. 300 or 310 MHz aren't allowed
"on the air".
vfone said:A λ/4 monopole for 300MHz is 25cm...which is approximately 5 times bigger than the actual PCB.
vfone said:The radiation resistance of a small-loop can be increased increasing the number of turns, or inserting within its circumference a ferrite core with high permeability.
RF circuitry
TriCode transmitters have two fixed antenna outputs – 300 MHz & 310 MHz.
C1, C4, C7 & C9 are the primary components of the 300 MHz antenna circuit. R4, R1, C8, Q1, R5, &
C11 are the means by which a coded message from the microprocessor, U1, may be transmitted on the
300 MHz antenna.
C2, C3, C5, & C10 are the primary components of the 310 MHz antenna circuit. R2, R3, C6, Q2, R6,
& C12 are the means by which a coded message from the microprocessor, U1, may be transmitted on
the 310 MHz antenna.
Yes, this could be seen without a schematic.Indeed they are two microstrip oscillators using transistors MMBTH10 (SMD E3), where the resonators are actually small loop antennas.
Yes, but do you think, the original poster knows how to?The easiest way is to let as it is and add another stage amplifier.
The oscillators are running from stabilized 5V, furthermore the operating point (and output "power") is defined by control voltage and the emitter resistor.Also what about the idea of simply increasing the voltage from 9V to 12V?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?