angular 5 *ngFor two array : I am getting array from two get method in angular 5. What i want is two combine those two array (JSON) in one array and print it in single for loop

my two arrays:-
       servers3 =[
         {
          sub:'sub',
          subDesc:'subDesc'
        }];

  public tableData:any;

i am using concat two combine two arrays like follows


      <table>
       <tr>
     <th>fileName</th>
     <th>icon</th>
     <th>fullPath</th>
     <th>sub</th>
     <th>subDesc</th>
     <th>image</th>
     </tr>
    <tr *ngFor="let item of tableData.concat(servers3)">
     <td>{{item?.fileName}}</td>
     <td>{{item?.icon}} </td>
     <td>{{item?.fullPath}}</td>
     <td>{{item?.sub}}</td>
     <td>{{item?.subDesc}}</td>
     <td><img src="{{item?.fullPath}}" width="200px" height="200px" alt="adawdawd"/></td>

     </tr>
   
     </table>

  

     </div>



And i am getting outp\put as follows:-

[![enter image description here][1]][1]


  [1]: https://i.stack.imgur.com/wHVrd.png

as you can see its not showing in one line 
each array completes individually

please give me solution if any one know the answer
thank you in advance 