How should I design my board to work with a ceramic chip antenna? - Page 1
Forum section: electronics / rf-microwave

author: technix
author_rank: Super Contributor
timestamp: May 09, 2019, 08:03:30 pm
content: This is my first DIY SBC. It has an AP6212 module for Wi-Fi and Bluetooth. I am using a chip antennaANT3216LL00R2400Awith it. Now how should I connect the antenna to the AP6212 module? Will a 47pF DC blocking cap + a pi-network (unpopulated for now) work? How should I translate the evaluation board design on the datasheet to an actual design on my own board?

author: shadow.dark
author_rank: Contributor
timestamp: May 10, 2019, 04:38:30 am
content: Do you have a vector network analyzer? It's easy to adjust the antenna with VNA. If not, you had better to find the ADS simulation model of the antenna. But simulation is just simulation after all.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 10, 2019, 04:41:12 am
content: Do what the module suggests in terms of layout, trace length and antenna type.Antenna components are generally tuned for 50 ohms, but YMMV if you use something that's not recommended.If you have access to a VNA, yeah, tuning is practical; you still need to know what impedance the module needs to see.Tim

author: technix
author_rank: Super Contributor
timestamp: May 10, 2019, 05:55:32 am
content: Quote from: T3sl4co1l on May 10, 2019, 04:41:12 amThere is no suggestions on the module's datasheet. I am taking references from other devices that makes use of the module instead.Quote from: T3sl4co1l on May 10, 2019, 04:41:12 amThat module uses 50 ohm RF. I am thinking of using as short traces as possible (no more than 2mm per segment, three segments and two 0603 passives from the module RF pin to the chip antenna.)Quote from: T3sl4co1l on May 10, 2019, 04:41:12 amQuote from: shadow.dark on May 10, 2019, 04:38:30 amI don't have VNA's.

author: shadow.dark
author_rank: Contributor
timestamp: May 10, 2019, 06:33:57 am
content: Is this component selected? If not, why not consider other well-documented components?

author: Heartbreaker
author_rank: Unknown
timestamp: May 10, 2019, 07:23:24 am
content: What kind of information is missing from the datasheet? Doesn’t fig 2 and 3 describe how to use the component?

author: ogden
author_rank: Super Contributor
timestamp: May 10, 2019, 07:38:31 am
content: Refer to datasheet/appnotes for chip antenna of your choice. Just one example of many:http://www.ti.com/lit/an/swra092b/swra092b.pdf

author: technix
author_rank: Super Contributor
timestamp: May 10, 2019, 07:57:18 am
content: Quote from: Heartbreaker on May 10, 2019, 07:23:24 amI need to figure out how should I scale the PCB part down to a few millimeters and make it work with other components and copper fills. My board is quite a squeeze.

author: shadow.dark
author_rank: Contributor
timestamp: May 10, 2019, 08:20:29 am
content: Well，If your PA output is 50 ohm, you may not need maching network., you can try to design a 50 ohm transmission line according to your PCB parameters, and then copy the Right half of the Data Sheet evaluation board as much as possible, with as much copper free space near the antenna as possible. Because you are totally blind, pray. (If you just want to make it work)PCB pattern size is determined by plate thickness and dielectric constant. It's not just scaling. There seems to be no information about the board in the datasheet.AND.If you need maching network.It is almost an impossible mission without VNA.

author: OwO
author_rank: Super Contributor
timestamp: May 10, 2019, 10:23:56 am
content: If your PCB is small relative to the wavelength then the example designs using the SMD antenna may not work well. The PCB is half of the antenna. Actually I would argue the PCB itself is the main part of the antenna, and the ceramic antenna merely provides a "virtual ground" so that currents can flow along the outer side of the ground plane and radiate.

author: technix
author_rank: Super Contributor
timestamp: May 10, 2019, 05:53:32 pm
content: Quote from: OwO on May 10, 2019, 10:23:56 amWhile my board is fairly large it space is at seriuos premium, so what is a good option for an antenna? Should I just admit defeat and use an RF connector like SMA or IPX and connect an antenna that way, should I use that ceramic chip antenna, or should I etch an planar inverted F there?

author: OwO
author_rank: Super Contributor
timestamp: May 11, 2019, 03:25:43 am
content: It is still possible to make it work with a small PCB, but you have to measure and tune the antenna yourself (or make an accurate simulation model).

author: ogden
author_rank: Super Contributor
timestamp: May 11, 2019, 08:56:29 am
content: Quote from: technix on May 10, 2019, 05:53:32 pmPerformance of each chip antenna is tested by manufacturer. PCB antenna performance is up-to your PCB house. It is not that easy to get consistent hi-freq RF performance on FR4. One batch of your PCB antenna could be ok, another could be off unless your manufacturer provides assured impedance /w tight tolerances and their control.