×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Reduction of a patch ground plane.

Reduction of a patch ground plane.

Reduction of a patch ground plane.

(OP)
Hi,
I'm designing a GPS receiver and I have a tricky size specification.
In order to meet this specification I have to use a patch antenna but the problem is that I will not be able to satisfy the groundplane size specification.
My question is do you know what kind of effect that will have on the patch ?
Detuning ?
Deformation of the radiation pattern ?
Modification of the input impedance ?
anything else ?

Thks for your help !

RE: Reduction of a patch ground plane.

Try serrating the edge of an electrically small groundplane.  The serrations match the field's impedance to freespace effectively making the groundplane appear electrically larger to the attached antenna.  The net effect is that the antenna pattern and impedance is restored.

RE: Reduction of a patch ground plane.

Suggestion: As an alternative to the above posting, go to the equation that you used for the patch antenna, and assess the equation potential variables for their modification to satisfy the ground plane size specification.

RE: Reduction of a patch ground plane.

Toon,

In general, as you reduce the size of a patch antenna's groundplane (or the ground of any antenna that is intended to operate against it) you will observe all of the effects you mention (detuning, pattern, impedance) as well as polarization.  There are some exceptions.  However, given your application is GPS and you have resorted to considering an electrically small groundplane area, then my guess is that you are stuffing this 'patch' antenna on some kind of handset.  If that is the case, you might follow the lead of many of the other GPS handset manufacturers/designers who utilize a quadrifilar helix antenna.  This type of antenna provides a superior hemispherical pattern and doesn't require driving against a groundplane.  Yes, it isn't conformal and does take more space external to the electronics package.  But the GPS mfrs have created some attractive packaging concepts that appear to be selling well.  Moreover, you can model the quad helix fairly well with simple commercially available moment method analysis software.  Alternatively you could contract the development of the antenna from one of the GPS antenna component mfrs out there such as MicroPulse or Tecom.  If the quad helix is unsuitable, you may wish to consider other types of conformal printed antenna elements such as flared quad slots in the outer sheild of a triplate configuration.  There are numerous ways to get the pattern/polarization/impedance/manufacturability/environmental features required for GPS reception.  

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources