Ceramic Antennas vs Stamped Metal Antenna

Hey

Anyone know the key difference between ceramic antenna and stamped metal antenna? Both goes under SMD/chip antenna. From what I understand the ceramic ones can be smaller and are easier to manufacture, while the metal ones are a bit better?

Stamped Metal Antenna Pictures

Ceramic Antenna

“Chip” ceramic antennae generally have poorer range than PCB trace or stamped metal MIFA / IFA designs. This Cypress app note gives a good overview:

https://www.cypress.com/documentation/application-notes/an91445-antenna-design-and-rf-layout-guidelines

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With antennas, almost all the time bigger means better. It has less to do with the type of construction, and more to do with the size of the elements. There are many chip antennas that are actually quite large related to center frequency.

Some ceramic antennas are just PIFA type with a high dielectric to get miniaturization. Most stamped metal antennas are of the PIFA topology.

However, most ceramic antennas are really just matched inductive loads. In many cases, I’ll use a ceramic chip antenna at a high frequency (e.g. 3 GHz) and extend a trace from it to get a lower frequency (e.g. 1575 MHz). The circuit for this is just like a monopole trace with inductor and capacitor components for size reduction (usually bandwidth reduction, too), but instead of two-three components it’s one component, the price break is sometimes better, and there’s less time spent fooling around on the VNA.

Here’s a nice page with chip antennas and stamped metal antennas. IMO, Ethertronics (now AVX) makes the best chip antennas in the business, but they are usually not no simple to use as, say Johanson. It’s important to know what is the topology of a chip antenna before you integrate it.

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Thanks both of you! This made things a lot more clearer. I just got a full feature ESP32 and that had a stamped metal antenna, while most seem to have PCB trace. Then I fell down the antenna rabbit hole and this ceramic appeared. What I am working on is to build something that controls multiple LED strips from scratch, so will need antennas.

Would also recommend everyone who don’t know much about antennas but are interested to read " AN91445 Antenna Design and RF Layout Guidelines.pdf" in this link. It is very compact and explain most stuff I have been wondering about regarding antennas.

I was looking for a ceramic/chip antenna fo a 2G/NB-IoT/M1 application, they all seems to require huge ground planes (>100mm). I wander how could be possible to integrate 2G/NB-IoT/M1 in a small IoT device obtaining reasonable RF performances…or should I give up the 700-900MHz range?

100mm ground plane is usually recommended for 900 MHz monopole antennas. You can put cleverly-placed slots in the ground plane to reduce the size somewhat, but it’s not going to make 100mm into 50mm without some losses to bandwidth or efficiency.

With some antennas it’s also possible to extend the ground plane with an inductive load (i.e. a long, meandering or spiral trace), which will decrease bandwidth but keep efficiency. The difficulty you have is that you need to support a spectrum that you have no control over.

The reality, though, is that cellular is not a low-power technology, regardless of what the marketers will tell you, so you’ll probably want an 100mm battery anyway. The ground plane can be above the battery.

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I do agree that a big battery would be needed, bu in this case a 30x60mm battery will be enough. The device has to last 4 months and send data every 3 days. Therefore I was looking for something to be integrated in that space. Would stamped metal antenna require less ground plane or they have the same requirement?

I don’t know exactly which stamped metal antenna you’re looking at, but most likely it will have the same ground plane issues. I recommend using an inductive antenna rather than a capacitive antenna (slot, PIFA), because in my opinion it’s easier to add controlled inductance to a ground plane than controlled capacitance.

You should build the device with the reduced ground plane size you are targeting. See if it makes any difference to your application (it might not be an issue). Then you can experiment with getting some extra efficiency in the low bands. This gets complicated to explain on a forum, but we can revisit it when the time comes.

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