Hello Everyone.!!
Can you please tell me the reason, Why should FR-4 substrate material be mostly used for antenna design?
Fr4 Material is cheap. that's why it is mostly used. moreover it is used for lower frequencies.
FR4 is a cheaper material. Also it is easily available in market as per our requirement.
I believe, rather than this their is no additional benefits of using this material.
Any one can consider Roger, Arlon and other material showing good behaviour to the high frequency applications.
Thank you.
The losses in FR4 increase as the frequency gets higher and start to matter significantly for frequencies above 1 GHz, becoming progressively more significant as the frequency goes above 1 GHz. The dielectric constant is not so well controlled as in 'proper' (designed for the job and more expensive) microwave materials.
As Kanhaiya Sharma says, it can be used where price is more important than efficiency, or where losses are minimised due to short track lengths or low Q being required (typically broadband).
Not just for patch antenna, mostly we used FR-4 substrate for low frequency designs because it is low-cost and easy available in the market. For high frequency designs we usually use high dielectric constant materials like Roger etc.
Dear Colleagues,
The choice of the substrate should consider its thickness and its permittivity. These characteristics impact on bandwidth. FR4 combines good electrical features, price and availability.
Better results can be achieved using materials other than FR-4. As FR-4 is sufficiently available and cheap, it is widely used for frequencies < 1GHz. Reason behind this is the permittivity of the substrate is almost constant for these frequencies. Also, FR-4 material is available in different thickness values than other ones which gives you more design flexibility.
As frequency is increased, the permittivity of FR-4 varies and loss in the substrate increases. But, if system is not very sensitive to losses and efficiency is not a major factor then FR-4 is used till almost 3GHz.
Dear Colleagues,
I have read:
"Unfortunately, the use of low-cost FR4 as the substrate introduces some additional complexity on the antenna design. This is due to the inaccuracy of the FR4 relative permittivity and its high loss tangent (around 0.02). Variations in the FR4 electrical permittivity can shift the operating frequency and the high loss tangent dramatically affects the antenna axial ratio and gain, resulting in poor radiation efficiency."
Design of Low-Cost Probe-Fed Microstrip Antennas | InTechOpen, Published on: 2011-04-04. Authors: D. C. Nascimento and J. C. da S. Lacava.
good electrical features, cost and availability.. mostly used at lower frequencies but losses increase as the frequency increases.
Please kindly tell the difference between FR4 and Arlon. Which one is best among the two?
FR4 material is cheap and readily available but not particularly good at microwave frequencies. If you want low loss and good efficiency then use something else. If you only need something cheap and cheerful use FR4. If you need to know better than that read the data sheets and do a proper circuit analysis to see what loss and variation in properties you can tolerate and then use the data sheets to find out which material will satisfy your requirements. Bear in mind that 2 dB less loss in a transmitter means 60% more battery life, and 60% bigger battery costs a lot more than a better circuit board.
So, at high frequencies (above 3GHz), which substrate should be preferred?
You can use RT/Duroid 5870, 5880, etc.
Please look at this link:
https://www.rogerscorp.com/acs/producttypes/6/RT-duroid-Laminates.aspx.
FR4 is mostly used in patch antenna design because of its lower cost and easier availability
FR 4 offers good flexibility for thinner substrate thicknesses at higher frequencies
Just due to low cost and its readily available. But there may be inaccuracy in results mainly to claim high gain etc due to higher loss tangent
Because FR-4 substrate have a suitable parameters for micsrostrip antenna such as Dielectric Constant (εr) is 3.9 – 4.7 4.4 @ 1 GHz (Supplier Isola) and Loss Tangent (tanδ) is 0.02 – 0.03, @ 1 GHz.
That is what is mostly used for PCB. Aside availability, embedding antenna on PCB becomes easier if and when it is designed on fr4
•Low Cost
•Easily available
•Relative mechanical and electrical stability
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