I'm designing a module around the nRF52832 SOC and I need some help regarding the single-ended microstrip antenna. I have three questions, so please bear with me.
- The first question is about how wide to make the feed line. I know I need a 50 Ohm trace, and using JLCPCB's calculator gives me a trace width of 11.55 mil. The problem is that when I consult other technical articles and use the KiCAD calculator, they give me a vastly different trace width of roughly twice the dielectric material of my board, which is ~3mm for 1.6mm FR4. However, this trace width is bigger than entire footprint pad and doesn't even fit...Do I just connect the LC filter with the 11.55 mil width from the manufacturer or make them as large as possible? I've checked the layout files from Nordic and they have used traces about the size of the pads, so I will stick to 11.55 mils until a reply to this question convinces me otherwise. I've also linked a picture of my routing below for clarity(The net named Antenna is also part of the feed line FYI).
My second question is regarding the antenna length. At 2.45GHz the wavelength is C/f = .125 meters, and quartering it yields 31.25 millimeters of antenna length. For now the length of the antenna is 31.25mm according to my own calculations, but Nordic's whitepapers throw me off by stating that the length should be 23mm without really clearly showing how they came up with that, and that is an 8.25mm disparity which will definitely affect the design. Which one is correct - 31.25 or 23mm?
The last question is about the antenna shape. I've linked a picture below with a hook-shape design that I replicated from another source. I don't know what shapes are 'better' than others, but I want to know whether or not there are glaring errors in what I have so far so I can fix them. If you read this far, thank you.