Questions tagged [impedance]
Impedance is the measure of the opposition that a circuit presents to an alternating current when a voltage is applied. This is a force of much interest to the radio amateur especially surrounding the connection to antennas.
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Easy way to adapt a CB antenna for a VHF transceiver
I have a very simple question To which I need a very simple answer.
I have several aerials that are "pre tuned" for 27mhz CB radio use, these are stud mounted on to snail connectors with 4m ...
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Why this dipole antenna has 75$\Omega$ to 300$\Omega$ matching network in it?
I have bought this antenna in the thrift market.
It seemingly is a dipole for FM radio bands - both telescopic arms extend around 1.5m total. But it is connected in a strange way - in the connector ...
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The idea that a non resonant antenna cannot accept current as well as a resonant antenna is a myth?
In a youtube video titled "Antenna Engineer Vs Ham Radio Myths! True or False?" the guy says this in the comments:
The idea that a non resonant antenna cannot accept current as well as a ...
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Input impedance of a shortened dipole antenna
I want to make myself a antenna for 40m and 20m wavelength band, but i don't have enough space for a full scale dipole, and even for more compact configurations like delta-loop or inverted v, so i ...
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What should a NanoVNA show for twisted pair impedance in TDR mode?
Thought I'd try doing some actual experiments with twisted pair feedlines and also just some general "non-coax" measurements and testing, but not until after I understood a bit more about ...
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What is the apparent AC voltage source caused by a mismatched impedance on the antenna or transmission line?
From Understanding how antenna mismatch can damage a transmitter
"The reflected wave appears to the transmitter's antenna port... as an AC voltage source... whose magnitude and phase depend on ...
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Impedance of Yagi boom model in NEC
When modelling a Yagi in NEC the radiation pattern is essentially identical whether a conductive boom is included or not, see pictures below. An explanation says this is a limitation of the method of ...
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How do I couple two VHF Small Signal Amplifiers together?
I have managed to build single stage VHF amps ok using the transistor's S-Parameters to determine the load and source reflection coefficients for a specific gain and stability considerations.
Simple ...
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Ohms & coax cabling miscalculation?
I measured the resistance for 15 meters RG6 cable, which showed 3 ohms on my multimeter !
I've got 0.7 ohms resistance on the multimeter itself when touching the negative and positive.
So 3 ohms - 0.7 ...
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What this E(EL) symbol does mean?
I can't understand what this E(or EL) symbol does mean. I know that Zo means impedance and I can calculate trace width according it, but what E symbol does mean?
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Why measuring Voltage and Current becomes difficult at Microwave frequencies? Why measure Power?
I have been reading some Classic books viz. Techniques of Microwave Measurements - Carol Montgomery, Foundations of Microwave Engineering - Collins, and some other google searches and they all claim ...
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SMA Connector Impedance
I am new to antennas, and am trying to create a monopole that connects to an SMA female to transmit a 2.4ghz wifi signal. I know that the antenna needs to be a multiple of 3.1cm in order to have the ...
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How can a low-impedance load can damage a FET final amplifier?
I believe I understand how an excessively high impedance can damage a final output power MOSFET (voltage rises until avalanche breakdown). But how does an excessively low impedance do that? If the ...
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What is the difference between antenna input impedance and its radiation resistance?
I got to know that the input impedance of the halfwave dipole antenna is given as:
Zin=1/Im* sin(β(H-|Z|))
where Im is the maximum current on the antenna( when excited with a 1 volt supply),
H is the ...
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How do you create a DC-blocking ground-shunt that looks inductive in an "L" match?
We are optimizing an impedance match with s2p models for an LNA and found that an "L" match with a serial cap and shunt inductor will optimize to provide +3 dB of output, versus using serial ...
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