Hazwan Hazwan I would recommend to go for Denim jeans. The main things are the permittivity and thickness. Try to go for lower permittivity value with more thickness. Because textile antenna will have issues with bandwidth and gain since the fabric is not same throughout the sample ( some places for fabrics, some places less) which affects the antenna performance. It will also cause big difference between simulated and fabricated antenna results. So, do the characteristics measurement in 8 to 9 different places and take average. All the best
Hazwan Hazwan , Denim is available everywhere. Country doesn't matter since these fabrics are widely sold throughout the world. Go to a local market and get it. I got mine this way few years back.