开云体育

Hi, Currently trying to design and tune a 1/2 end fed antenna (RF is applied on one end), I am looking for the correct method to measure its impedance. As this one is very high I don't know the right

I recently wrote a program to renormalize S-parameter impedance. This lets you measure a filter with a 50 ohm VNA even though the design impedance is higher. In the course of testing the program, I

Wow ! Thank you so much to every one for taking your time in helping me. I truly appreciate it. @Siegfried @John I finally did it. I've cut down my RG174 down to the shortest length I could (35mm).

And also remember line lengths on/in the dielectric are shortened by the reciprocal of the SQRT of the dielectric constant (I assume FR-4?....nominally 4.2). Dave -

Nico, A couple of points to consider. 1. I can't tell from your PCB photo if you had tracks on both sides of the board in order to implemented a transmission line from the matching network to the

I don't know that shortening it even more makes all that much difference. You can guestimate the loss and to a first order, you're looking for reasonably flat S11 across your band, right? So if 174

Let me apologize if my yesterday's post was not clear. The pictures I posted are actually the result of the recommendation you gave me. I took a 30cm RG-316 cable I have and calibrated at the very

Putting your hand near the antenna (or, really, anything) will also "load" it with a lossy medium, improving the match. As noted before, though, most people do this by using a tool to design it (e.g.

1) Do you have the eval board? (Always useful to look at a "known good" implementation) 2) I'm not sure it's expecting copper under the coil. The figure in the data sheet sort of looks like only the

Yes, you're on the right track. However, I'd strongly recomment you place several appropriate clamp-on ferrites on your feedline right where it exits the assembly. Also place a few at the VNA,

you should albsoutely calibrate on cable end and use one as short as it is practical (just a few inches would be best!!) only THEN you have exact values to type into simsmith .. then calculate parts

John, Thanks once again for the precious advices. As I’ve put the antenna exactly as I t has been manufactured, could I simply populate the matching network instead of stretching the spirals ?

Nicolas, Your results actually look pretty good. An SWR of 2.4:1 represents a loss of only 17%. Small changes in the spacing of the turns on your antenna should enable you to put the minimum SWR at

Another jig in this post…. /g/nanovna-users/message/20848

Clifton, My test jigs and other members were discussed several years ago in this topic. There are 125 messages and lots of good info. /g/nanovna-users/message/20809

Once again, Thanks to all of you for your inputs. Poorly translated from french, I would say that I did not know in what type of gearbox I was going to put my finger in ! Well, I ran some other

Can you show a closeup picture of the TEST JIG for your NanoVNA please. ________________________________ Sent: Sunday, February 23, 2025 5:01 PM To: [email protected] Subject: Re: testing

Can you show a closeup picture of the TEST JIG for your NanoVNA please. ________________________________ Sent: Sunday, February 23, 2025 1:26 PM To: [email protected] Subject: Re: testing non-50

as shorfter the cable as better your setup dg9bfc sigi Am 23.02.2025 um 20:32 schrieb Nico via groups.io:

Nico, You don't necessarily need more connectors. You could calibrate at the end of your RG174 cable by detaching it from your board, then using a small 50 ohm chip capacitor, an open circuit, and a