My computer w DSL service is on the backside of our house. We have a guest house 800 feet away on the front side of the house. My Router provides a good Wi-Fi signal for Ipad, MAC on the front side of the house. What 'Booster' with Directional External Antenna should I buy so that we can get Wi-Fi service at the guest house? There is an unimpeded view through a window from the front side of the house to the guest house? Thanks.