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 - W?LEV
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On Mon, Feb 24, 2025 at 9:57?PM Jim Lux via groups.io <jimlux=
[email protected]> wrote:
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 it's <1 dB round
trip, and you get -10 dB S11, then it's probably really something like -9.
How picky is your source about reflected power?(most low power sources
aren't very picky)
-10 dB is only 10% reduction in radiated power (assuming it doesn't
reflect back to the antenna and get radiated <grin>)
Those antennas aren't super efficient anyway.
-----Original Message-----
From: <[email protected]>
Sent: Feb 24, 2025 10:21 AM
To: <[email protected]>
Subject: Re: [nanovna-users] Am I in the right track ?
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 end. Then I made a 6in
RG-174 from that end that connect on the pcb. I added a 760ps delay to
compensate for the RG-174. Tonight I will try to shorten it as much as I
can and some measurements.
The radio transceiver I intend to use has a 50ohm output. The feedline I
created on the pcb should also be a 50 ohm line. I made the pcb fabricated
with controlled impedance. This way, the fab house provides the dielectric
constant of the pcb stack up and provide trace width recommandation to
achieve the desired impedance, which I followed. The antenna I chose is
also 50ohm.
I will follow up.
Thanks again
--
*Dave - W?LEV*
--
Dave - W?LEV
