During my recent Wireless Adjuster II class I got introduced to Airtool Pi (new tool created by Adrian Granados). If you have been using Airtool or Airtool 2, you will certainly love this, cost is $14.99 and it is worth every penny.
All you need is a WLANPi (Neo 2 is what I used; you can build you own as discussed by Adrian here).

Airtool Pi gives us an ability to perform similar functions as Airtool/Airtool2 using our iPhone or iPad and WLANPi as an external sensor. These captures can be easily transferred to your laptop for further analysis in Wireshark or Wi-Fi Explorer Pro.
Configuring Airtool Pi is really easy as shown in the video. I think “Hostname” should be changed to “Hostname/IP” but it isn’t a big deal.
After capturing all I had to do was airdrop it to my Mac and open it up in Wireshark or Wi-Fi Explorer. Easy to use, reasonably priced and the whole setup can be carried in a small bag or side pockets.