Matronics Email Lists Forum Index Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
 
 Get Email Distribution Too!Get Email Distribution Too!    FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

406 ground plane

 
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> AeroElectric-List
View previous topic :: View next topic  
Author Message
Dave Saylor



Joined: 11 Jan 2015
Posts: 209
Location: GILROY, CA

PostPosted: Wed Oct 25, 2017 2:48 pm    Post subject: 406 ground plane Reply with quote

I'm planning to install a new ELT.  It comes with a "shark fin" antenna that incorporates the 406 antenna and the antenna for the internal GPS.  It has no 121.5 capability.  It has a metal base plate, which I thought was sufficient for higher frequencies.

However, the installation instructions call for a ground plane of at least 120 square inches, and preferably 300 square inches.
Am I missing something?  Why would an antenna operating at such high frequencies need such a large ground plane?  Isn't the rule that the radius of the ground plane should match the length of the antenna?
--Dave


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

_________________
--Dave
KWVI
Back to top
View user's profile Send private message
nuckolls.bob(at)aeroelect
Guest





PostPosted: Wed Oct 25, 2017 3:09 pm    Post subject: 406 ground plane Reply with quote

At 05:46 PM 10/25/2017, you wrote:
Quote:
I'm planning to install a new ELT. It comes with a "shark fin" antenna that incorporates the 406 antenna and the antenna for the internal GPS. It has no 121.5 capability. It has a metal base plate, which I thought was sufficient for higher frequencies.

However, the installation instructions call for a ground plane of at least 120 square inches, and preferably 300 square inches.

Am I missing something? Why would an antenna operating at such high frequencies need such a large ground plane? Isn't the rule that the radius of the ground plane should match the length of the antenna?

--Dave

The 1/4 wave ground plane at the lowest frequency of
interest is 300/406 meters = 0.74M x 39.36 in/M x 0.25
yields a radius of 7.25"

7.25 (squared) x 3.1416 = 166 square inches . . . which
meets the "120 mininum".




Bob . . .


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
rv10pro(at)gmail.com
Guest





PostPosted: Wed Oct 25, 2017 3:11 pm    Post subject: 406 ground plane Reply with quote

300 sq. in. would be 17.5 x 17.5 and using six radials of 1" wide copper adhesive tape is commonly used to propagate a solid ground plane. 0/60/120/180/240/300 degrees as the line of longitude runs.
John
On Wed, Oct 25, 2017 at 3:46 PM, David Saylor <saylor.dave(at)gmail.com (saylor.dave(at)gmail.com)> wrote:
Quote:
I'm planning to install a new ELT.  It comes with a "shark fin" antenna that incorporates the 406 antenna and the antenna for the internal GPS.  It has no 121.5 capability.  It has a metal base plate, which I thought was sufficient for higher frequencies.

However, the installation instructions call for a ground plane of at least 120 square inches, and preferably 300 square inches.
Am I missing something?  Why would an antenna operating at such high frequencies need such a large ground plane?  Isn't the rule that the radius of the ground plane should match the length of the antenna?
--Dave



- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
Dave Saylor



Joined: 11 Jan 2015
Posts: 209
Location: GILROY, CA

PostPosted: Thu Oct 26, 2017 5:24 am    Post subject: 406 ground plane Reply with quote

OK, 120 it is.  Thanks again Aeroelectricians!

On Wed, Oct 25, 2017 at 4:08 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
Quote:
At 05:46 PM 10/25/2017, you wrote:
Quote:
I'm planning to install a new ELT.  It comes with a "shark fin" antenna that incorporates the 406 antenna and the antenna for the internal GPS.  It has no 121.5 capability.  It has a metal base plate, which I thought was sufficient for higher frequencies.

However, the installation instructions call for a ground plane of at least 120 square inches, and preferably 300 square inches.

Am I missing something?  Why would an antenna operating at such high frequencies need such a large ground plane?  Isn't the rule that the radius of the ground plane should match the length of the antenna?

--Dave

  The 1/4 wave ground plane at the lowest frequency of
  interest is 300/406 meters = 0.74M x 39.36 in/M x 0.25
  yields a radius of 7.25"

  7.25 (squared) x 3.1416 = 166 square inches . . . which
  meets the "120 mininum".
 



  Bob . . .


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

_________________
--Dave
KWVI
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> AeroElectric-List All times are GMT - 8 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


Powered by phpBB © 2001, 2005 phpBB Group