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I remember a form of low loss cable that was popular in the 1980-90's the size of rg-8 (can't remember the brandname). It had a spiral plastic dielectric and I used a run of it for a UHF antenna.?

exactly. You want low epsilon of the dielectric and foam tube or a spiral of plastic meets the requirement nicely. To that extent it's like minimizing dielectric losses in microwave cables, but for a

Maybe that explains an automobile antenna I found once in the past.? I was surprised that what looked like coax was actually a piece of plastic tubing, maybe 1/4" I.D., with a thin wire running

The big requirement for coax on voltage probes is low capacitance - you generally don't worry about impedance. That's because the antenna is largely capacitive (so it looks like a voltage in series

What I would do is use a NanoVNA to measure the impedance over 88-108 MHz right at the connector that plugs into the radio. Average the measurements for several cars. Then design a network that

The high-Z coaxial cable is more for the AM portion of the radio. On AM frequencies, especially the European version, the "stinger" antenna is nothing but a capacitive probe. Consequently, it presents

Hey everyone, True beginner in RF here for a classic alignment question. Sorry if this is inappropriate or the wrong group, I'm not sure where to ask such question. I suppose the NanoVNA would be a

If you used this BNC to Banana adapter, you are adding about 2 pF or so of shunt capacitance across the feed point of your test dipole. At 500 MHz for example, this is about Xc = 159 ohms. This is

This is the part of LF model that don’t work basically because is the wrong frequency region…

Hi Patricio Thanks for clarification , I do not understand this graphic zone circled on red color below 73's Nizar

This chart shows the typical behaviour of a loosy coaxial cable over frequency. Basically there are two models , the low frequency model in this case the dielectric loose are very small then G tends

Hi With same coax, same method, same NanoVNA H4 (1.2.40 DiSlord) surprisingly i have some different Zc values for 50Mhz & 100Mhz 50Mhz ---> Zc = 49.0 Ohm 100Mhz ---> Zc = 43.5 Ohm 73's Nizar 2Mhz --->

Hi Patricio I do not understand this chart, can you explaine it more pse. 73's Nizar

Oops! I should have R >> jwL, not R >> jwC. My error. 73, Maynard W6PAP

An interesting chart. Note that below about 300 kHz, the imaginary component of the characteristic impedance can no longer be ignored and, if you are working on any cables at voice frequencies or

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Hi Jim Lux "L , C & R exhibit some frequency-dependent variation; they do not have a perfectly flat response across frequency. This behavior depends on the dielectric material used, skin effect and

Not unexpected Zc is sqrt( (R+jomegaL)/(G+jomegaC)) Mostly determined by L/C, but the R is in there too, and it goes up as frequency goes up, because of skin effect. For HF the dielectric loss (G) is

Interesting , the Zo uses to rise a little when the frequency goes down.

Hi for same RG213 cable (25m length) loaded by a 50.3 Ohm resistor I used the same circle methode centered on smith graph with the renormalized Z0 impedance ( option added by DiSlord) for different