Ground Sphere Antenna Reference Design
Added by Jeremy Wright about 10 years ago
This warning was in the documentation for the eggbeater antenna reference design.
Be warned that some PVC pipes have very poor dielectric characteristic in VHF or UHF. In
this case, tuning of the antenna will not be possible e.g. high SWR, cannot find resonance etc...( it
was the case here for the UHF antenna). If this is the case, the loops must be mounted on a better
quality dielectric component.
While the reference to SWR tells me this is mainly a concern when transmitting using the antenna, we need to be sure that it won't cause Ground Sphere any problems. This would also make a good argument for being very consistent on the components that are placed in kits. The same style PVC coupler from two different vendors could apparently have different dielectric characteristics.
Replies (2)
RE: Ground Sphere Antenna Reference Design - Added by Aaron Harper about 10 years ago
SWR affects transmission, but the underlying issues such as impedance mismatch affect the coupling between the antenna and receiver as well. PVC has some issues when it comes to higher frequencies (2+ GHz) as well as a tendency to build static if given half a chance. This is one of the reasons the ground for the ground plane and the terminal lugs are in direct contact with the PVC and the PVC body of Ground Sphere is kept as small as possible.
RE: Ground Sphere Antenna Reference Design - Added by Jeremy Wright about 10 years ago
Good to know. Thanks Aaron.
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