All true,
BUT
Just to keep from being mislead,
I said what a choke ring antenna does,
You have described how it is so good at its job.
The Main purpose of the choke ring's, hi impedance, 1/4 wave, tuned
thingies, around the antenna is to keep reflected Signals from BELOW the
antenna from sneaking around into the antenna. It does not effect the
signals above the 10 deg or so elevation point.
The choke rings are a necessary to get cm type survey accuracy,
but a pie pan shield /ground plane pretty much does the same thing at the
GPSDO 1ns (1ft) level,
where you don't need 100 db rejection for signals below the antenna.
What I've found; don't even need to be lucky.
Just put an 8 inch pie pan in the right place, facing the right direction.
ws
***************
Hi there,
just to prevent from making mistakes ...
You can have two different accessories for GNSS antennas:
1) a ground plane
it prevents the antenna from receiving signals from beneath the
antenna (from the ground, roof or whatever is beneath)
... so this could be your pie pan normally
2) a choke ring
it creates an area of high impedance around your antenna;
because it is just a (set of) simple quarter wave waveguide(s) with
short-circuit on one end, you can build it from a sheet of metal by
yourself; you only need to calculate the sizes for your waveguide on
the L1 frequency ... and if you are a lucky guy and your pie pan fits
these sizes, you probably can use it for that ;-)
Best regards
Martin
****************
Is there a design for a choke ring to add to my existing L1 GPS antenna ?
Yeah
If you are using it for GPSDO work where a ns is good enough and you don't
need cm accuracy,
It is called a pie pan with its Lip turned up.
A choke rings blocks reflected signals from below the antenna from effecting
the signals, a pie pan works pretty good at that also.
ws
***************
Hello The Net:
Is there a design for a choke ring to add to my existing L1 GPS antenna ?
While there may be some variations to the exact dimensions of a choke
ring to a specific type of L1 antenna, either patch, helical, etc.,
I suspect there is some commonality to the design dimensions.
I am looking to start construction and I will be using a cheapie
patch/puck antenna.
Stan, W1LE
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