How to pass a base address with query input parameters for a WCF service using web socket in ASP.NET with C#?

A base address cannot contain a Uri query string.
Parameter name: item

Below is the  base address I need to send as request 
<pre>https://10.15.15.15/CBWSO/wso?entityDetails={   
                  
                    

                     {                                     
                     "requestData": "2834367eec9be180739b628ae73e89ceac49ad575a3d00876105fe0321b3fc4a" ,
                     "requestkData": "2834367eec9be180739b628ae73e89ceac49ad575a3d00876105fe0321b3fc4a" 
                    }
                    
                  
                & entityId=123}

wss://10.15.15.15/CBWSO/wso?entityDetails={   
                  
                    

                     {                                     
                     "requestData": "2834367eec9be180739b628ae73e89ceac49ad575a3d00876105fe0321b3fc4a" ,
                     "requestkData": "2834367eec9be180739b628ae73e89ceac49ad575a3d00876105fe0321b3fc4a" 
                    }
                    
                  
                & entityId=123}

string strHandShakeRequest = string.Empty;
    try
    {
        Logger.Log("Fetching of Encryption With AES for handshake Starts", LogFilename.WebPageLog, 3, MethodInfo.GetCurrentMethod().Name);

        string HandShakeParentUrl = hsk.HandShakeReqParentUrl;

        string RequestKeyData = hsk.requestKData;

        string RequestData = hsk.requestKData;

        string EntityID = hsk.EntityId;

        string json = @"



             {
             ""requestData"": """ + RequestKeyData + @""" ,
             ""requestkData"": """ + RequestData + @"""
            }


        ";




        StringBuilder strRequest = new StringBuilder();
        strRequest
       .Append(HandShakeReqParentUrl)
       .Append("=")
       .Append("{ ")
       .Append(json)
        .Append("& ")
       .Append("entityId=")
       .Append("")
       .Append(EntityId)
       . Append("")
       .Append("}");

        strHandShakeRequest = strRequest.ToString();



        Logger.Log("Fetching of Encryption With AES for handshake Ends", LogFilename.WebPageLog, 3, MethodInfo.GetCurrentMethod().Name);
    }
    catch (Exception ex)
    {
        throw ex;
    }
    return strHandShakeRequest;

Uri baseAddress = new Uri(strHandShakeRequest);
                       ServiceHost host = new ServiceHost(typeof(WebSocket_Stub.Service1), baseAddress);