If your objective is to connect two devices which support only ethernet to an existing WiFi network, you could do so by configuring an AirPort Express (for example) in Client mode connected to your existing WiFi network. Then you could use the LAN and WAN ports on the AirPort Express to connect your dish receiver and DVD player. This concept is called "bridging" rather than extending a network, but in your case I think it is what you need. This solution does not provide you additional WiFi service at your devices, it simply serves as a "wireless ethernet cable" back to your modem/router which creates your wireless network.
Could do the same with an AirPort Extreme Base Station I believe, if you needed more than the two ports.
If I have misunderstood your requirement, I apologize.