I have an active HF, LF, and VLF antenna I purchased on eBay. I have seen an article for SDR. https://www.rtl-sdr.com/roundup-software-defined-radios/ I am especially interested in SDR Rx to run on software on a tablet computer. I have iPad Mini 2 and Kocaso Windows and Kocaso Android tablet computers. I am interested in recommendations.