Is there any matematerial which can reflect right handed circular polarization into Left handed circular polarization or vice versa of the EM waves operating in ultra-wide band?
Dear Hussain Askari
I think this is not possible especially if you are interested in ultra-wideband performance, but what is the exact application you want or why you want to convert from one to one and not just change the feeding or the antenna element to have the desired polarization?
Because if you want simultaneously both polarizations or choose one time RHCP and other LHCP, what you can do is using an ultra-wideband antenna with dual polarization (RHCP and LHCP).
See this article for more details it provides UWB from 2GHz to 14GHz (BW of 150%) using conical log-spiral with dual-circular polarizations and stable performance over the whole band.
K. A. Abdalmalak et al., "Ultrawideband Conical Log-Spiral Circularly Polarized Feed for Radio Astronomy," in IEEE Transactions on Antennas and Propagation, vol. 68, no. 3, pp. 1995-2007, March 2020, doi: https://doi.org/10.1109/TAP.2019.2949700
Article Ultrawideband Conical Log-Spiral Circularly Polarized Feed f...
I am not sure I understand exactly what you want to do. However, metameterials are not needed for reflecting RHCP into LHCP. Any reflecting material turns RHCP into LHCP.
Any good conductor, e.g. a metal surface, reverses the direction of circular polarization on reflection, for all frequencies for which it is a good conductor.
Dear George Slade and Malcolm White
Thanks for the productive replies, but using metal will reverse the propagation vector too so, for example, it will have the radiation down instead of up if the antenna in the XY plane. But anyway it is not so clear for me what Hussain Askari wants because what I understand that he wants to keep the same radiation direction so if it radiates RHCP up he want to put a layer to convert this to LHCP.
If this is true, so using metal will not be enough, for example, if we have a planar RHCP spiral it will radiate RHCP upward and simultaneously LHCP downward, and putting metal up will just focus the most of radiated power to downward directions which was already there without the metal.
Anyway, let's wait for Hussain Askari to confirm what he wants exactly maybe I have misunderstood his question
Thank you dear Kerlos Atia Abdalmalak, George Slade and Malcolm White for giving me your time to answer above question. Actually, I am designing an antenna which is bidirectional in nature and it has dual polarization i.e RHCP on +z-axis and LHCP on -z-axis. Thus, I want to reflect back the LHCP with the reverse polarization (RHCP) into +z-axis in order to get maximum gain. I guess conductor can be used as reflector but it makes the design complex and large size so, I want to use meta-material surface as a reflector.
No idea about using meta-material for such purpose, hope you will find further answers soon.
By the way, which kind of antenna are you using, I think it is spiral, is it? and how much relative BW and gain do you want to achieve?
The problem for the conductor "ground plane", it will affect the antenna impedance and destroy its self-complementary behavior especially if it is close to the antenna. Usually, for UWB performance, people use cavity and absorbers in the downside of the antenna but this causes 3dB losses so it will not be high gain.
Or if the high gain is more important for you and you can relax the size requirement, you can use a dielectric lens which can provide gain of about 20:30 dBi but size will be several lambdas as in [1]
[1] E.R. Brown, A.W.M. Lee, B.S. Navi, and J.E. Bjarnason, “Characterization of a Planar Self-Complementary Square-Spiral Antenna in the THz Region,” Microwave and Optical Tech Lett, vol. 48, No. 3, pp. 524-529, 2006.
To have something in the middle and solve such trade-off between gain and size requirements, you can use conical spiral which can provide gain of 10dB and dimensions of 1 lambda if you want UWB of 150%, or more compact if you do not want such huge band
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