How is the effective size of a dipole/monopole printed antenna calculated?
What is the scale factor/effective Er that should be used?
Most of the equations I have found on the web are related to Microstrip or Patch antennas, which is not the same as the above case because of the GND below the antenna.
You can't have an ungrounded monopole. It always has to have another half, either a reflection in even a partial ground, or another part which makes the other half of a dipole.
A monopole will usually be quarter of a wavelength long. If it is bent then it is quarter wave following all the bends, although if it is bent a lot this is not quite accurate. For an electric monopole it can be shortened if there are caps or bulges at the far end, which use up some of the length. They act like extra capacitance at the end. Things that look like inductors can be put near the bottom and will also make it shorter.
A printed patch monopole has the patch which is the capacitor, and the pin which is the inductor. If the pin is short the patch may be about quarter wave radius if the pin is in the middle. If the pin is at one end then the patch may be a quarter of a wavelength long.
If you mean a vertical antenna printed on one side of a dielectric, with a horizontal ground across the bottom, that just looks almost like a metal antenna, and needs to be a quarter wave long. It won't work without a ground. It is hard not to have some kind of ground. If it is fed by co-ax then the outside of the coax will behave as a not very good ground. You can put chokes on the coax to stop this happening, but then the monopole is badly matched and doesn't radiate much.
Hi,
I meant, for example, a printed monopole on a 1.6mm FR4 substrate. Of course with ground countrpose, but not beneath it. How is the QWL, scaled when it is attached to the FR4.
It hardly changes the wavelength at all. It depends how much of the 1/6 or maybe 1/3 wavelength diameter cylinder (reactive near field) surrounding the metal has dielectric in it. A sheet of FR4 hardly occupies any of this
- G. Kumar and K. P. Ray, Broadband microstrip antennas. Artech House, 2003.
- C. A. Balanis, Antenna theory : analysis and design, 4th ed. Wiley, 2016, pp. 190-192
Hi Pierre,
I am asking about printed non-microstrip antennas.
Looking for an equation that describes the effect of substrate loading on resonance frequency.
Dear @Yechiel Asraff,
After carefully rereading your question and your comments/reactions to every answer posted here, it seems like your antenna structure doesn't match or have any close similarity with any existing design in the literature.
If that is the case, I would suggest to share the antenna configuration for a better guidance or help from other researchers.
Because the explanations given above by @Malcolm White stated well the problem you are in. From there, your antenna is more likely to match with any of the configurations provided in the suggested references. If not, kindly the share the design here. Thanks
There a lots of antenna like this and they are in the design books. Here is an example Article An L-Sleeve L-Monopole Antenna Fitting a Shark-fin Module fo...
Where the gaps between conductors are small compared to the thickness of the board the dielectric has more effect.
You will find useful relevant information in the following recent paper:
Article Eight-Element Compact UWB-MIMO/Diversity Antenna with WLAN B...
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