Probably because you do not ask and hardly provide any details nor requirements.
As @kersing already mentioned
For one of the cheaper outdoor suitable gateways check the following topic MikroTik LoRaWAN gateways and concentrator boards (available e.g. here). But if that will suit your requirements is not at all clear.
Using low power long range WAN networks is more complex and less evident than buying a TV, connecting it to an antenna wall outlet and then start watching.
If you want to setup your own environment you will have to investigate and do some homework yourself. If this is not for you then maybe you should consult a solutions provider.
No one is going to present you a complete working solution that matches your needs on a silver platter (unless you pay them for it).
We are not here to do your homework 
. You can find information and advice about antenna’s here (search is your friend): The BIG and SMALL ANTENNA topic part 2.
I guess Lora is a great idea… but not what it sells to be.
It is not clear what your expectations are and what they are based on (shiny sales brochure or study of LoRaWAN technical specifications and real use cases), but your current setup with single indoor gateway (with ‘sub optimal’ antenna) and some nodes is not exactly representative for the quality, possibilities and usability of LoRaWAN in general.
LoRa is actually ‘just’ a radio modulation technology. It doesn’t sell anything, people do.
If you want more help from others it helps to clearly specify your use case, provide requirements and other relevant details and ask more targeted questions.
For experiments you do not need a different gateway at the moment. You can start with a decent antenna with proper placement and during the tests place your current gateway on the roof with mains power and LAN extension cables (in case you use wired LAN) but only with dry weather conditions of course. You can also start experimenting with other nodes. But do not expect a solution that works perfectly for your case right out of the box.