Jeff Edwards is correct and he did all the original testing of the “alternate” antenna.  I had the aviation antenna that comes with the WSI system installed in my ES and had marginal (at best) performance.  It was installed on top of the fuselage with an adequate ground plane. 

 

The marine antenna, part no. AT1560-1, works without ground plane considerations and is buried in the tail (like Jeff did).  Performance is excellent.  We have a dozen of these antennas in stock and cost is $300.  If you want one, contact Rachael at (541) 504-8300

 

Regards,

 

Kirk Hammersmith

Direct-To Avionics

www.d2av.com