View source for Antenna Design and NanoVNA

== Introduction ==
NanoVNA is a simple but powerful tool to analyze antennas.

VNA: Vector Network Analyzer

SWR: Standing Wave Ratio measures the degree of mismatch between a transmission line and its load. SWR is a measure of what is happening to the forward and reflected voltage waveforms and how they compare in size.

See more info at https://nanovna.com/

== Theory ==

=== Main Screen ===

* Start/Stop frequency at the bottom
* Marker
* Calibration status on the right side. 
** C0-C4: Corresponding calibration data is loaded
** c0-c4: Corresponding calibration data is loaded, but the frequency range has been changed.
** D direcitivity error
** R Error correction is applied: Reflection
** S Error correction is applied: Source
** T Error correction is applied: Transmission
** X Error correction is applied: Isolation/ Crosstalk
* Reference position. Yellow Horizontal line. (DISPLAY -> SCALE -> REFERENCE POSITION)
* Trace status. Trace formats are following
** LOGMAG: Logarithm of absolute value of measured value
** PHASE: Phase in the range of -180 ° to + 180 °
** DELAY: Delay
** SMITH: Smith Chart
** SWR: Standing Wave Ratio
** POLAR: Polar coordinate format
** LINEAR: Absolute value of the measured value
** REAL: Real number of measured value
** IMAG: Imaginary number of measured value
** RESISTANCE: Resistance component of the measured impedance
** REACTANCE: The reactance component of the measured impedance

* Battery status

=== Calibration ===
NanoVNA should be calibrated always when the frequency range is changed. 

* CAL RESET
* Connect OPEN standard to port 1 (CH0) and execute CAL CALIBRATE OPEN.
* Connect SHORT standard to port 1 (CH0) and execute CAL CALIBRATE SHORT.
* Connect the LOAD standard to the port 1 (CH0) and execute CAL CALIBRATE LOAD.
* Connect the LOAD standard to port 1(CH0) and port 2 (CH1) and execute CAL CALIBRATE ISOLN. If there is only one load, connect the LOAD standard to port 1 (CH0), the port 2 (CH1) can be left unconnected.
* Connect cables to the port 1 (CH0) and port 2 (CH1), connect the cables with the through connectors, and execute CAL CALIBRATE THRU.
* End calibration and calculate error correction information CAL CALIBRATE DONE
* Specify the data number and save. CAL CALIBRATE SAVE SAVE 0

=== Antenna Measurements ===

Use Port 1 when measuring one port devices. 

NanoVNA draws the measurement result on the screen as a graph of the
measured quantity versus frequency or on the [https://en.wikipedia.org/wiki/Smith_chart Smith Chart].

M1: Marker position

For antenna measurements:
* Traces
** CH0/ S11 (Yellow), refl:  LogMax
** CH0/ S11 (Green), refl: Smith
** CH0/ S11 (Yellow), refl: SWR
** CH1 (Purple): Nothing
* Frequency Range
** STIMULUS: Start/ Stop.
* Calibrate
** CALIBRATE -> RESET
** CALIBRATE: OPEN, SHORT, LOAD and DONE. SAVE to location.
* MARKER -> SEARCH -> MINIMUM

Before each measurement:
* which traces we want to display (up to four or three plus Smith Chart)
** DISPLAY -> CHANNEL -> CH0 Reflect for antennas. 
* trace channel (CH0 REFLECT or CH1 THROUGH) for each trace separately
** DISPLAY -> TRACE. Click multiple times.
** Active Trace. 
* trace format (unit of measurement of each format)
* scale (how many units of measurement per each horizontal line, for each trace separately)
* reference position for each trace separately
* sweep frequency (stimulus frequency range)
* calibrate the NanoVNA

== Antennas: 433 MHz ==

=== Monopole  ===

<gallery>
Antenna monopole 18-8.png|18.8 cm; Resonances at 220MHz and 484 MHz.
Antenna monopole 18-8-2.png|18.8 cm; Closer look at 220 MHz resonance.
Antenna_monopole_18-8-3.png|18.8 cm; Closer look at 484 MHz resonance.

Antenna monopole 20-8.png|20.8 cm; Small resonances at 244MHz and 484 MHz.
Antenna monopole 20-8-2.png|20.8 cm; Closer look at the other resonance.

Antenna monopole 16-8-3.png|16.8 cm; Other resonance.
</gallery>

Quarter wave wire antenna; <math>L=fc/4 = 3 \times 1084\times 434\times10^6=0.173m</math>

{| class="wikitable"
|+ The resonances of quarter wave monopole antennas measured with NanoVNA and using its black short cable. Calibrated first to 100-900 MHz and to the two resonances. 
|-
! Length !! Resonance 1 !! Resonance 2
|-
| 16.8 cm || 236 MHz -> 229 MHz || 524 MHz -> 516 MHz
|-
| 17.3 cm || 237 MHz -> 232 MHz || 516 MHz -> 508 MHz
|-
| 18.8 cm || 220 MHz -> 216 MHz || 484 MHz -> 496 MHz
|-
| 20.8 cm || 244 MHz -> 237 MHz || 484 MHz -> 487 MHz
|}

=== Dipole ===

https://www.electrical4u.com/dipole-antenna/
- Folded Dipole Antenna
- Two-Wire Folded Dipole Antenna
- Three Wire Folded Dipole Antenna (Folded Tripole)