What is a PHSNA?
This comes from the term « Poor Ham’s Scalar Network Analyzer » It is just a sheap antenna analyser.
PHSNA Features :
- Analysis band: 1 to 30Mhz
- Ad9850 or AD9851
- Arduino UNO
- Remote Display: autonomous mode (optional not yet developed)
- Wheatstone bridge measurement coupled with an AD8307
- 1206 CMS Components (Ebay Listing here Bill Of Materials For phsarduino)
- Cost between 20 € and 30 €
PCBs are pre-order, if you are interested, thank you to send me an email :
f4goh at orange.fr
(8.5€ including shipping to France, 11€ international)
It’s been a long time since I wanted to try this scalar analyser. Indeed there are many descriptions on Internet and various schematics like this article.
Most of the time, the results of this analyzer are displayed on an LCD screen and does not have communication with PC software.
I wanted to overcome this disadvantage by using the AntScope software for Rigexpert analyzers while having the possibility of operating in Autonomous mode.
2 Schematics description
The Arduino drives an ad9850/51 programmable oscillator. The output signal is then amplified by a MMIC SGA3486. Then after attenuation, the sinusoidal signal attacks a Wheatstone bridge used in many different and varied electronic stuffs.
The differential voltage from the bridge is injected into a logarithmic amplifier AD8307. The output Vout of the AD8307, continuous is converted by Arduino ‘s 10 – bit internal ADC. The reference voltage of the ADC is delivered by a LM385Z-2.5V regulator on the AREF input,
It will remain a last calculation to perform, Rs, the equivalent resistance of the antenna. Indeed, the AntScope software protocol needs two parameters:
– Rs – Resistance, series form
– Xs – Reactance, series form
Rs is calculated by the arduino, but Xs is not possible to calculate with this scalar antenna which does not determine the phase. This parameter always remains at zero.
This is why we call this montage: Poor Ham’s Scalar Network Analyzer, since the phase is not used compared to a vector network analyze that gives more informations, but little more expensive to build on HF bands.
An HF VNA has already been published here:
However to made wired RF antennas, the PHSNA will do the job as well for an cheap price.
3 Assembly and tests:
You will find here in the ZIP all the PCBs, implementation of the components and the software.
The assembly does have any problem. Start by soldering the SMD resistors as well as the 1206 format capacitors. Continue the SMD implementation with 2 inductors and ad8307.
Finish the SMD by the LED face up. (at the edge of the map on the AD9850 side)
If you do not know how to weld CMS by hand without reflow oven, watch this demonstration.
Then solder the LM385Z-2.5V, C9 capacitor and connectors.
Perform a non-continuity test between the VCC and the Ground before turning on the Arduino, it’s safer.
Note about the amplifier
Depending on your supply, you can change the reference and R1 polarization resistance.
|MMIC Amplifier||R1 Résistor (ohms)|
|msa0386 (my configuration on board)||10|
4 The software :
In order to facilitate the programming, I directly provided the HEX file to be programmed in the arduino UNO.
Depending on your DDS choose the right configuration
If you are using an AD9850, leave the J1 strap open
If you are using an AD9851, solder a bridge on the J1 strap
Put a strap on J6 (pin 2-3) this is for AD98850 RESET PIN connection
The programming is done via the Xloader software provided in the ZIP mentioned above.
Remember to program the arduino UNO WITHOUT the sheild (PHSNA card) disconnected. You never know what he had as a program in the ARDUINO UNO, (new or already used?)
If the drivers are not recognized, install the Arduino IDE environment because the drivers are contained in the program, unless you use a Arduino « Chinese clone ». There is a good chance that they are CH340 / 341 drivers. Fortunately, you will find these drivers in the ZIP.
if you don’t know how to install CH340 Drivers watch this video
To find COM port number, take a look at peripheral manager
5 First start
Insert the PHSNA card on the Arduino. Power on the unit with a USB type A-B cord. The red power LED on the AD9850 should light up. Check the voltage at the terminals read LM385Z (2.5V)
Start a serial terminal software (eg Hterm). Set the port as shown on the screenshot below.
Without connecting a 50 ohm load or an antenna, enter « cal » and enter
The aduino makes a measurement of 1 to 30Mhz. Then save the calibration value in its internal EEPROM memory. Its value should be between 100 and 200 depending on the amplifier mounted on the card.
7 Using AntScope
If you are interested in the serial communication protocol, know that it is open and available at the following address.
Download the AntScope software, and follow the following screenshots in order.
The software help is here, but a bit light.
Be careful, the options will be limited with the PHSNA.
It will be necessary to be satisfied with the Measurement menu in order to obtain the SWR curve and it is what we want. D1 Led blink during scan.
I compared the PHSNA plot with a miniVnaPro from mini radio solutions
It will be necessary to check that the signal delivered on amplifier output is sinusoidal.
To do this, launch Antscope software, then in the menu Measurement click on RF on / off The frequency must be 10Mhz,
The output voltage must be clean (see screenshot below). In case of distortion, check the ad9850 output signal and amplifier output.
This small HF analyzer will do a good job in your radio shack. Mounting is easy to build and components are available on Ebay or Alliexpress. I would like to add an ESP8266 interface (WIFI server) to view the SWR curve on the Smartphone
73 and see you next time.