KR-400 rotator: www.dl3lar.de/KRx00.html
Yagis and SWR: www.g4ztr.co.uk/amateur-radio/yagis-and-swr
2m yagi with gamma match: www.george-smart.co.uk/antennas/144mhz_yagi
X-yagi van OZ2OE: oz2oe.dk/radio/xyagi/xyagi.html
X-polarization: dg7ybn.de/Building/xpol.htm
Circular polarization: www.qsl.net/sv1bsx/antenna-pol/polarization.html
Distance / mapping: acscdg.com
Terrain mapping: www.heywhatsthat.com/profiler.html
Calculating coplanar wave guides: chemandy.com/calculators/coplanar-waveguide-with-ground-calculator.htm &
www.disk91.com/2015/technology/hardware/design-a-50ohm-impedance-net-for-rf-signals/
Interesting site for shortwave info other than amateur radio: radio.chobi.net
Nagoya: www.nagoya.com.tw
Jun-Mao www.jun-mao.com.tw - exotic coax seller
FT-RF: www.taiwan-antenna.com
RimTai: www.rimtai.com