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I wouldn't try to make a really broad band filter with coupled lines, your gap will have to be really small. The design would be impractical, there are better topologies for practical design. A series of shunt resonators separated by Z0 quarter wave TLs might be practical.
The last cap on a third order loop filter is shunt to ground, which you could say is parallel to the VCO input capacitance. The VCO input cap is considered in the design of the loop filter, if as you say above, the vari-cap is around 40p and the last cap of the loop filter is 1n then the...
grega_primc
Fvm is correct when he suggests tuning the inductors to resonate at the blocking frequencies with a parallel cap. But it appears you have chosen inductors that have a SRF at these frequencies already, so there is no need to tune. I would put a shunt cap between the two inductors...
I am not sure what a 13MHz and 27Mhz RF choke is. If it is an inductor with self resonance (sharp attenuation near 13 and 27MHz) then you should put a shunt cap between them otherwise the resonance between two SRF inductors might yield unexpected results. I would probably use a ceramic close to...
If you look at the equation,
GTX + GRX = 20log(λ / (4πR)) - 10log(P0/Pr)
and realize -10log(P0/Pr) = S21 then you should be done. You may never know P0 and Pr absolutely but their ratio is the only quantity necessary to determine the gain of the unknown antenna. Of course trying to get a far...
Several here have mentioned a SRD for the comb generation. This will work well but the phase noise of the amplifier to drive the SRD will be a factor, in fact it is probably much higher than the crystal. In general, a BJT will have less phase noise than a FET type amp. Also the desired comb...
The purpose of the LO is to switch the mixer. The mixer diodes are shorted in pairs causing the IF signal to be flipped in polarity at the rate of the LO signal. This alternating polarity applied to the IF (or RF) creates the up/ down conversion. Therefore the LO signal must be strong enough to...
If the device has poor match and the cables to connect are are 1 meter with a dielectric of 2 you could get 100MHz ripple like you see. Put a 3dB pad at the end of each cable (device side) you should see NF+3 and less ripple.
The easiest method is to determine the impedance of each stage from the ideal lumped. The ideal filter has series LC pair and shut parallel LC alternating. The impedance of the LC pairs is sqrt(L/C). That is the easy part, there are many way to implement in a printed circuit. The series...
Imagine a body of water that is not at rest, say a river for example. The velocity of the water at any given point could be described by a vector field. It is easy to realize that a small paddle wheel placed in the river flow could be forced to rotate, since the water in the center of the river...
I used microwave office for the design. I haven't used that in a while but I remember there being a Lange coupler element.
I simulated the linear response only with the S-parameters provided by the manufacturer, Avago ATF-34143 transistor.
This model has the noise match for the input. I was...
The Lange coupler is a space efficient way of getting a broadband 90 degree coupler. This is used to split the input to two amplifiers driven 90 degrees apart. The outputs are summed up in phase with an identical coupler.
When two amps are driven this way the reflected signals will be isolated...
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