Chip Antenna vs Miniature Helix

[Chetan Joshi]

Hello,

I am trying to choose antenna for my PCB. My design is very small in size (7 x2 cm²). I am using a cc430 micro controller with integrated radio module. The radio module does not contain antenna and related circuitry and it is upon the user to decide how to use the antenna. With a frequency of 433 MHz, it is very difficult to operate with a printed antenna design and I think I have to choose discrete miniature antennas.

I checked on websites such as mouser and farnell where I found two types of antennas at 433 MHz frequency range.

1. Chip Antenna
2. Miniature Helix ( Both SMD and through hole configurations)

But I cannot decide on one of these two. Can anyone suggest why is one of these better than the other.
Also, can please somebody explain me the reason of one being very pricey (chip antenna) while the other is very cheap in comparison.

For reference, I am adding the datasheets of the components:
https://www.farnell.com/datasheets/311705.pdf
https://www.farnell.com/datasheets/1391934.pdf
https://www.linxtechnologies.com/resources/data-guides/ant-xxx-hexx.pdf


Chip antenna


Helix wound around plastic


Thanks a lot for your replies.

 

[FvM]

TI has several informative application notes comparing different anntennas https://www.ti.com/product/cc1101#appNote

Generally speaking both are electrically small antennas, involving a small bandwidth (not a particular problem for 433 MHz band) and also a resonant impedance matching that is sensitive to "hand effect" and other objects in the vicinity. Usually, the larger of two electrically small antennas gives better performance.

 

[vedagarbhamsandeep]

These chip / small antennas are basically 0-1dBi show off antennas and not of great help when you need to transmit data for more than 15-20m. If you have no restrictions on external antenna you could as well terminate the 50ohm pcb trace with a 50ohm connector and use a 3-5dBi omni antenna which would surely give you a much better performance as compared to internal and miniature antennas. All depends on the application / feasibility to design depending on customer / who so ever !

 

[vfone]

I would go for helical. Ignoring their datasheets I am pretty sure if you compare them side by side, helical would be better.

 

[Chetan Joshi]

Hi, thank you for the reply, is it the size that makes you think so?

 

[E Kafeman]

Both these antennas are monopoles. Monopole antenna performance will very much depend on shape and size of ground plane as ground becomes the second half of the total antenna. A very short ground length from antenna view, and it doesn't matter how good the numbers was in the antenna data sheet, if it was measured using a longer/wider ground.
Proposed tuning components values must be adjusted if your ground plane not have same shape as in the application example.
Assume that also the chip antenna is a helix and antennas embedded in material with high dielectric constant which normally result in a bit narrow bandwidth.
Narrow bandwidth can make tuning component values more critical and mistuning due to hand-effect costs more performance loss compared to a air-cored coil.
If you not can measure required impedance matching, is air core a more safe selection.