Arduino Antenna Tuner by K3NG
I have built one unit which was intended to be a prototype. It worked so well that I haven’t built another one and the prototype continues to be used in my shack on a nearly daily basis. The bottom line is, it works rather well. I would eventually like to build a QRP model with latching relays and sleep mode.
https://blog.radioartisan.com/arduino-antenna-tuner/

ATU for EFHW 20/40m antenna & Icom TRX by ON7EQ
This project describes an ARDUINO based automatic antenna tuner, for an end fed half wave (EFHW) antenna, dual band for 20 & 40m.
https://www.qsl.net/on7eq/projects/arduino_atu.htm

Automatic antenna tuner using an Arduino by PA3HCM
The Arduino board is a fantastic tool for rapid prototyping, and can help radio amateurs in lots of homebrew projects. I wanted to demonstrate that it is very easy to build an automatic antenna tuner with the Arduino.
http://www.pa3hcm.nl/?p=336

CI-V based remote antenna switch by IK5PWC
In summer, 2011 I decided that it was time to automate also this task in my shack, using something able to switch the antenna based on the currently selected band on the radio. Of course, the issue was how to do it, since all commercial solutions I found wouldn't fit all my needs.
https://www.ik5pwc.it/en/civ_remote_antenna_switch_1.html

HF Antenna Analyser With Arduino and DDS Module by Dr Phil
... What I really wanted was an antenna analyser. These devices can test the quality of the antenna match at any frequency over the HF bands. Unfortunately they are also very expensive, so I set about considering whether I could make my own.
https://www.instructables.com/id/HF-Antenna-Analyser-With-Arduino-and-DDS-Module/

Intelligent antenna matrix switch by ON7EQ
An ideal tool for connecting your IC-706 or IC-7000 to more than one antenna and having them switched automatically. You could as well use it to drive a 5 bands BPF ... or develop an antenna tuning unit, a magnetic loop variable condenser stepper motor drive etc ...
https://www.qsl.net/on7eq/projects/arduino_ant_matrix.htm

RF power & SWR meter by ON7EQ
This sketch will readout RF power and SWR from any SWR bridge (for example 'monimatch' type). As this 'monimatch' type of bridge is frequency dependant, the meter must be calibrated for every band.
https://www.qsl.net/on7eq/projects/arduino_pwr_swr.htm

Rotator Computer Interface and Controller by K3NG
This is an Arduino-based rotator interface that interfaces a computer to a rotator or rotator controller, emulating the Yaesu GS-232A/B and Easycom protocols which are supported by a myriad of logging, contest, and control programs.
https://blog.radioartisan.com/arduino_rotator_controller/