Looking for the substrate material to build a patch antenna

[timmarshall]

Hi, everyone

I am currently looking for some kind of flexible plastic material to build my wireless capsule endoscopy patch antenna substrate, however, I am really stuck with that and there is very few resource available on the online store. Could you please give me some suggestions on how to access such kind of material?

Thank you,
Marshall

 

[jeeudr]

Re: looking for the substrate material to build a patch antenna

You might want to search for keywords such as 'biomedical' or 'implantable' together with just 'antennas'. There is a lot of work being done in this area, and a preliminary search even turned up one from EPFL : [ https://infoscience.epfl.ch/record/166129/files/EPFL_TH5110.pdf ]

Take a look at the substrates used in published articles and reasons mentioned for their choice of substrates. That should provide a good starting point. Narrowing down based on broad vendor datasheets is usually much more complicated.

 

[jiripolivka]

Re: looking for the substrate material to build a patch antenna

Depends on the frequency and application. Implantable devices require stringent control of materials; only Teflon and stainless steel may be considered.

 

[timmarshall]

Re: looking for the substrate material to build a patch antenna

Thank you for advice. Biocompatability should necessarily be a big concern in my project. However at the current stage I am still looking for some flexible material to build the antenna prototype which will be tested in open space or human phantom. The operating frequency is 433 MHZ. I found some researchers utilised some kind of LCP (liquid crystal polymer) to build the substrate, but the same problem haunted as I try to buy a suitable one on the internet.

 

[streamlet]

There are commercial UHF RFID tags implemented on flexible plastic materials. According to measurement of the permittivity of those materials, it seems they are PTFE-based. However, a major problem of the existing materials is that they are thin, which places a challenge to narrowband patch antenna.

Besides, according to the info provided by a plastic supplier, if high permittivity is not required, the hunt for the flexible plastic material will be easier.

Last but not the least, there is an article published on a recent issue of IEEE Microwave Magazine. It presents a method to generate a flexible material by mixing ceramic and polymer. The advantage of this artificial material is that it can deliver a high permittivity while maintaining the flexibility feature.

 

[jiripolivka]

Re: looking for the substrate material to build a patch antenna

Thank you for advice. Biocompatability should necessarily be a big concern in my project. However at the current stage I am still looking for some flexible material to build the antenna prototype which will be tested in open space or human phantom. The operating frequency is 433 MHZ. I found some researchers utilised some kind of LCP (liquid crystal polymer) to build the substrate, but the same problem haunted as I try to buy a suitable one on the internet.

You can certainly find interesting new materials and designs. Tissue impedance is quite lossy at 433 MHz, so to start I would recommend to use a commercial antenna. Check Murata for dielectric antennas and get ready to encapsulate it in Teflon or some plastic to improve in=tissue matching. The radiation pattern will also change substantially as you will find.