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calculate input capacitance
Read datasheet on actual CMOS circurit, try to find spice model on used circurit or last step - measure itself with network analyzer or simular measure bridge tools (need high skill measure knowledge)...
Cmos circurit exist in many generation (to speed increase...
Read some RS485 application note to make new idea - its easy find on Internet.
RS485 it's self a dumb differentiell buffer/driver with no protocol, i think you can using eight of them (one RS485 each dataline) per port as driver and simular reciver (also RS485) in B unit and simple shielded...
How fast ?
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if new design - skip above solution with parallell port drive to unit and use 'local intelligence' with PIC in slave unit and using serial communication, RS485 and twisted pair between units. RS485 can going with 2 Mbit, multidrop and 1-2 km wire lenght
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If interface...
Yes, is more or less whole point to use this very expensive instruments. Most of then can show measured data in polar, smithchart and retangular form in re, im or mag, dB, and angle notation. Search 'hp 8753' on Internet and you find lot of information.
It also very important this instrument...
Re: is there any tool for impedence matching tool in linux ?
I use time to time 'Vipec' (find on sourceforge) for simple RF-network analyze work including matching work (can inport S-parameter files) - meny tools/tune is really useful for adjusting parameters and update all charts in near...
Look at Smithchart ???
This form of grafical chart is invented around 1930 for make easier calculate on impedance and make more human friendly show of impedance behavior if measure enough sample in different frequency - and now in real time uppdate in VNA is very helpfull i matching and tuning...
Re: battery
you must have seriosly overloading if battery got owerflow...
How much overflow ?
if loss < 10% of cell volyme is practical not need refill acid to continue good working, make only a note acid weigt i sligth lower than normal in full charged state (charge properly and note spec...
return loss bridge schematic
Is a 'standard' weathstone bridge
toroid-line is a balun to make possible measure unbalance between each 'leg' in bridge width extern unbalanced detectors/reciver/RSSI-circurit...
size, quality and frequency range on toroids in balun make limits on usable...
Γ= 75 - 40 / 75 + 40 = 0.3043
S11 = 10 log10(0.3043^2) = -10.33 dB
S21 = 10 Log10(1 - (0.3043^2)) = -0.422 dB
ie 10 dB return loss and 0.42 dB inserting loss if you connect 75 Ohm antenna directly to 40 Ohm input.
use this solution if you not find other unwanted behavior.
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If not...
Re: impedance matching.
Air hanged big power plant lines and old air hanged phone/telegraph line have different situation compare to compact cable - this line have big space between conductor and make higher inductance and lower capacitanse - so this line going to Z= √L/C-state already on...
power line impedance matching
Ah, You also read and use textbooks simplified formula!!!
textbook have written mostly two simplified case:
for audio frequency 0 - ~20 kHz) ie. g << ωr and r >> ωl is simplified to
γ = α + jβ = √(jωrc)
α = β = √((ωrc)/2) or γ = √(ωrc) |_ 45 degree
Z =...
complex impedance speaker wire
And RG58 (one kind of 50 Ohm cable) itself have around 6390 Ohm and -45 degree characteric complex impedance on 20 Hz, 1013 Ohm and -44.92 degree on 800 Hz etc.
Is not easy task to make power matched coupling with near zero Ohm impedance in amplifier, up to...
Antenna is not problem - bud LNA in first step in reciver is a different case...
Most LNA in consumer equipment begins to puke around -40 - -30 dBm and make intermodulation in strong multicarrier enviroment.
GSM need least 9 dB signal over interfrence margin to recive readable data - more...
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