Feasibility of designing 2.4GHz antenna - Page 1
Forum section: electronics / beginners

author: willthamic
author_rank: Newbie
timestamp: October 18, 2021, 04:53:28 pm
content: Hello,I'm doing undergraduate research at my schools radiology lab helping design a wearable imaging system. Being wearable, size is a big constraint and we're trying to shrink everything we can. We don't want it to be tethered to anything, so we transmit collected data over wifi to a computer for further processing. Currently we use a CC3220 to relay the data over wifi, and the somewhat beefier PIC32MZ for some data processing before transmitting.I've been given the task to investigate ways to shrink this board, and potentially get it down to one processor. The ESP32 seemed like a good candidate, appears to be a bit more powerful than the pic and has the wifi built in. There are some pretty small boards out there with antennas built in, different micro, but the BlkBox BB-E01P is an example but is unfortunately out of stock.Another option would be to design the antenna ourselves, but this seems pretty complicated. I have some experience in PCB design, but I don't have experience in RF design. And while I've found a couple resources, I don't have any sense of scale for how difficult this is/how precise it has to be.Here's what I've looked at:- This pretty comprehensive manual:https://www.cypress.com/file/136236/download- This article:https://circuitdigest.com/article/how-to-design-a-pcb-antenna-for-24ghzIs this something that could be reasonably done by a beginner-ish person, and what would be the best path to take?The cyprus manual discourages the chip antenna. The wire antenna gives off a sense of being simple, while the PCB route seems intimidating. Does anyone have a recommendation on how to approach this? Any tips on alternative micros are also welcome, the ESP32 doesn't have the fastest UART which isn't exactly ideal.Thanks!

author: Terry Bites
author_rank: Super Contributor
timestamp: October 18, 2021, 05:10:20 pm
content: Take the easy way out kiddo.

author: Fred27
author_rank: Unknown
timestamp: October 18, 2021, 05:12:08 pm
content: I think the simplest options are:Use a chip antenna. If the performance is good enough for your needs then don't stress about whether it's optimal.Copy a proven PCB antenna design.

author: Boscoe
author_rank: Frequent Contributor
timestamp: October 18, 2021, 05:19:01 pm
content: Check out thishttps://www.ti.com/lit/an/swra161b/swra161b.pdf

author: Peabody
author_rank: Super Contributor
timestamp: October 18, 2021, 05:29:20 pm
content: There's a TI app note on a PCB antenna for 2.4GHz:https://www.ti.com/lit/an/swra117d/swra117d.pdfA wire antenna could be just a piece of tiny coax with a bare 28-30mm at the end. But then you probably have to mess with U.FL connectors.Then there are ceramic antennas.The Lolin D1 Mini has a PCB antenna. The D1 Mini Pro has a ceramic antenna and a U.FL connector for an external antenna, the selection being determined by the position of a zero-ohm resistor.

author: willthamic
author_rank: Newbie
timestamp: October 18, 2021, 06:46:13 pm
content: Terry Bites:I'm certainly tempted too.Fred27:My impression from these documents was that chip antennas we're pretty finicky. Is this true or am I misreading it?Copying a design seems like a good idea, but I thought that the exact parameters would depend on the manufacturing specifics of the board, and other board elements like how my ground plane is designed. Is this something I have to worry about or is it basically a copy-paste?Boscoe:This is a good resource thanks.Peabody:This as well. I wouldn't expect the U.FL connectors to be an issue unless I'm missing something.Unfortunately the D1 Mini is almost bigger than our current board, which comes out to about 40mm x 25mm.

author: m98
author_rank: Frequent Contributor
timestamp: October 18, 2021, 07:18:19 pm
content: Unless you need to meet specific performance targets or want to actually create a commercial product, don't stress it too much. I've already accidentally used WiFi modules without an antenna, worked perfectly well until I looked at the RSSI.

author: ogden
author_rank: Super Contributor
timestamp: October 18, 2021, 07:40:03 pm
content: Quote from: Fred27 on October 18, 2021, 05:12:08 pmRight. Use existing solutions as much as possible to save time & resources for main subject of your project/research.

author: David Hess
author_rank: Super Contributor
timestamp: October 18, 2021, 08:49:33 pm
content: Quote from: Fred27 on October 18, 2021, 05:12:08 pmI agree, and there are many cookbook designs for PCB antennas to copy.

author: willthamic
author_rank: Newbie
timestamp: October 18, 2021, 09:32:17 pm
content: Thanks everyone, this has been quite helpful!

author: perieanuo
author_rank: Frequent Contributor
timestamp: October 19, 2021, 06:58:20 am
content: Quote from: Peabody on October 18, 2021, 05:29:20 pmin some medical 2.4G comm device made with some nordic chips, the designer (this one was't me) used just some tiny wire like Peabody pointed, like 3cm, never measured his length, and worked 100% reliable for up to 30 comm devices in master/slave topology in some big treatment rooms in hospitals (the wire was inside a semi-transparent 'sanded' plastic cylinder that was used also to transmit the LED light for transmit if i remember well, ir was kinda funny).but for your app, wire is ugly but if you have the guts just test this with any wire you like, see how modifying length and position works with your environment, this will give you a clue on designing the pcb antenna