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Re: RETURN LOSS thoughts de k3eui
It's the same in other fields.? In optics, density is the negative log of the transmission, so something that transmit 0.1 of the incident intensity is a positive density of 1.? Density is like loss, the more of it, the larger (more positive) the number.
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On Wednesday, June 30, 2021, 6:08:59 AM MDT, Barry K3EUI <k3euibarry@...> wrote:
I had not anticipated this would lead to so many comments. Thank you for great insights. Maybe it feels more correct if we just say? RETURN? (S11) and leave the word "loss" out. I mean for an antenna, I'd like the S11 signal to be very very small, because I hope the forward signal is turned in an EM wave, and not much is relfected back towards the source. I ran into another interesting concept while giving a "talk" on the Nano VNA. WHAT IS THE NET CHARGE ON A BATTERY? WHAT IS THE NET CHARGE ON AN UNCHARGED CAPACITOR? WHAT IS THE NET CHARGE ON A CHARGED CPACITOR? WHAT IS THE NET CHARGE ON AN ANTENNA WHILE RADIATING AND EM WAVE? This led to another question: At any given moment, when generating an EM wave, is one-half of a dipole negative, and the other half positively charged?? ? What is the NET charge then on the whole antenna? That was interesting.....? all because of a talk on Nano VNA. This little gadget brings to life many ideas about our understanding of basic physics. de? k3eui de k3eui |
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Thx for this very helpful hack - this helps me a lot during FW development.
But it is sufficient to add the wire (easy task), no need to change the resistor R5 from 1K (original) to 5K (as H4) - this is more difficult, especially if you do not have this SMD value at hand :). I checked the schematics, the JP P1 connects BOOT0 directly to Vdd, so it doesn't harm if you connect via 1K to Vdd. Martin |
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Re: RETURN LOSS thoughts de k3eui
I had not anticipated this would lead to so many comments.
Thank you for great insights. Maybe it feels more correct if we just say RETURN (S11) and leave the word "loss" out. I mean for an antenna, I'd like the S11 signal to be very very small, because I hope the forward signal is turned in an EM wave, and not much is relfected back towards the source. I ran into another interesting concept while giving a "talk" on the Nano VNA. WHAT IS THE NET CHARGE ON A BATTERY? WHAT IS THE NET CHARGE ON AN UNCHARGED CAPACITOR? WHAT IS THE NET CHARGE ON A CHARGED CPACITOR? WHAT IS THE NET CHARGE ON AN ANTENNA WHILE RADIATING AND EM WAVE? This led to another question: At any given moment, when generating an EM wave, is one-half of a dipole negative, and the other half positively charged? What is the NET charge then on the whole antenna? That was interesting..... all because of a talk on Nano VNA. This little gadget brings to life many ideas about our understanding of basic physics. de k3eui de k3eui |
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Re: Charger for Nano
I repurpose old micro-USB cables and 5 V chargers with these USB-C adapters:
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Adding a sleeve of shrink tubing to cover the joint ensures they don't easily come apart. Dave N9ZC On Tue, Jun 29, 2021, 12:52 PM Jim Lux <jim@...> wrote:
On 6/29/21 8:01 AM, Mikek wrote:I pulled my NanoVNA-H out just to charge it, it has been a while since Iused it. It powers up fine and the indicator says the battery is low.I see the connector is not the usual micro USB on my phone, but is aUSB-C. Did I get a charger with my unit, that I have lost?I have no clue how I charger my Nano! I do have the 10" USB-C cable. Ibought it from R&L.Thanks GuysMine didn't have a charger but had a USB-C cable - you charge it using |
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Re: Charger for Nano
Good that you found it, although I should think that any USB-C cable should work. The simplest solution is perhaps to charge it from your computer. However that begins to get problematic if you are like many of us who have a growing collection of USB powered and connected devices. To that end I just purchased one of these:
It seems to be of decent quality and so far works well. I have no affiliation with the seller or product, and over the last few days I have looked at a dizzying selection of interesting USB charging gadgets available now online. I have a somewhat different solution also on the way from NewEgg, we'll see how it works. 73 -Jim NU0C On Tue, 29 Jun 2021 08:36:40 -0700 "Mikek" <amdx@...> wrote: Thanks to all that responded. |
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Thanks for the Group
I purchased a NANOVNA-H some time ago to learn and hopefully solve a problem. With an attic full of antennas that have all coax running to a box in the shack, I no longer knew which cable came from which antenna. Well labeled 25 years ago but four of the five are no longer readable. The Nano solved the problem along with some great guides from this group and nanovna-saver I have identified all four with their SWR patterns. TNX
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Re: RETURN LOSS thoughts de k3eui
Traditionally, the B in dB is capitalized because it someone's name.? Alexander Graham Bell. V, A, W, F, H, C etc are also capitalized because the units are named after people, Volta, Ampere, Watt, Faraday, Henry, Coulomb...
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On Tuesday, June 29, 2021, 8:35:10 AM MDT, Cliff <kd4gt.tn@...> wrote:
»å±ð³¦¡¤¾±¡¤²ú±ð±ô noun a unit used to measure the intensity of a sound or the power level of an electrical signal by comparing it with a given level on a logarithmic scale. db is what I would call "unitless". It must always be referenced to some starting point. Sometimes we add a reference like dbm or dbW when talking about power. Loss is a negative situation. Gain is positive. If I "loose" $20 gambling, I subtract 20 from what I had in my pocket at the start of the game. But going to basic algebra, if I subtract a negative number, I actually add [100 - (-20) = 120]. An amusing story from the TelCo industry: A station engineer had low levels coming into the transmitter from the studio over the phone line. He had the phone company tech there trying to fix the problem. The engineer asked the tech to turn up the gain on the circuit. The tech said he was not able to do that. After more discussion, the phone tech allowed that all he could do was to turn down the loss. OK! Problem solved! |
Lou W7HV
Ho-Ro
Barry K3EUI
Dave Merrill
Jim Shorney
Richard Clemens