Please refer to the following article, it covers the implementation of a wideband spiral antenna but without metamaterial.

I think you may start with and improves the gain, radiation patter, impedance matching,.etc with using of a metamaterial array as a reflector.

"Enhanced Broadband RF Differential Rectifier Integrated with Archimedean Spiral Antenna for Wireless Energy Harvesting Applications "

Check this paper:

A New Compact Double-Negative Miniaturized Metamaterial for Wideband Operation.

Hope it helps

You can also check transmission line based metamaterials for wideband operations.

Thank you Nitin

Hello Nitin,

I checked and worked on the design related to this paper "A New Compact Double-Negative Miniaturized Metamaterial for Wideband Operation.".

To get 2.4 and 5.8 GHz , I had to increase the gap between the antenna and the metamaterial which is not desirable for wearable applications.as the total thickness is going to be too thick. Would you please be able to guide me on metamaterial design covers 2 to 6 GHz but the thickness is less too.

Thank you in advance.