what is the best antenna ,to be used to transmit the2187,5 kHz ,beside the mast antenna,to cover up to 1000Km?

Answer 1

For the best compromise of cost vs performance I would go with a 1/2 wavelength inverted V. Support the center feed point at 150-200 ft above ground. This antenna will be broadly non-directional. The feed point will be close to 50 Ohms Z. For additional gain and small broadside directivity. You can lengthen the V to One wavelength. This creates two half wavelengths in phase. The feed point will be high-Z at a voltage loop requiring a matching network. Hope this helps you out.