GPS Antenna

google "Wilkinson" "hybrid power divider" and "IRE Transactions" before
saying stuff like this.

The answer to the OP's question is that yes, it is possible, fairly easy,
and needs an active antenna to do the job right.

Jim



Also, to keep impedances correct, the splitter will likely either have to
be
lossy, or active.

-Cory

RST Engineering wrote:

Also, to keep impedances correct, the splitter will likely either have to
be lossy, or active.

google "Wilkinson" "hybrid power divider" and "IRE Transactions" before
saying stuff like this.

What's the matter?

To divide the antenna power to several receivers
always means some loss to a single receiver. In
an ideal case, a passive divider to two branches
will show a loss of 3 dB to both branches, and
this means no power loss in the divider.

An active divider can compensate for the losses
with an amplifier.

The division losses always exceed zero if the
impedances are not properly matched, which will
show more than 3 dB in divide to two.

--

Tauno Voipio, avionics engineer
tauno voipio (at) iki fi

"Tauno Voipio" wrote in message
...
RST Engineering wrote:

Also, to keep impedances correct, the splitter will likely either have to
be lossy, or active.

google "Wilkinson" "hybrid power divider" and "IRE Transactions" before
saying stuff like this.

What's the matter?

The "matter" is defining "loss". In general, we do not say that a device is
lossy unless the incoming power is greater than the outgoing power. In the
case of the Wilkinson (or any variety of hybrid) splitter, the "loss" (if
any) is measured in tenths of a dB for any decent design.

There are a series of truly "lossy" resistive splitters that are not
acceptable for this particular application.



To divide the antenna power to several receivers
always means some loss to a single receiver. In
an ideal case, a passive divider to two branches
will show a loss of 3 dB to both branches, and
this means no power loss in the divider.

An active divider can compensate for the losses
with an amplifier.

With something on the order of 26 dB active gain in the typical external GPS
antenna, and with a loss of something on the order of 8 to 10 dB in the
normal run of coax from antenna to receiver, you are still something like
16-18 dB ahead of the game over a stock passive antenna. A 3 dB reduction
in signal level (30% in voltage) will not be noticeable.

Why would you go to the hassle of an active splitter at 1.7 GHz. when it is
not necessary? Remember, a good engineer can build a bridge that will stand
up to maximum design loads plus safety factor. An EXCELLENT engineer can
build a bridge that will stand up to maximum design loads plus safety factor
JUST BARELY.



The division losses always exceed zero if the
impedances are not properly matched, which will
show more than 3 dB in divide to two.

Like I said, in a properly designed hybrid, losses are measured in feathers,
not bricks.



--

Tauno Voipio, avionics engineer
tauno voipio (at) iki fi

Jim Weir

Avionics Technician at 16

Avionics Engineer at 22

Avionics Engineer Emeritus after 40 years in the 'biz with any kind of luck
at all in a couple more years.
(Emeritus = "on the shelf")

Why would you go to the hassle of an active splitter at 1.7 GHz. when it is
not necessary? Remember, a good engineer can build a bridge that will stand
up to maximum design loads plus safety factor. An EXCELLENT engineer can
build a bridge that will stand up to maximum design loads plus safety factor
JUST BARELY.

Oh what the heck!!!
Let's make this real world...
A good engineer can build a levy that will stand up to a Level 5
hurricane plus safety factor. An EXCELLENT engineer can build a levy
that will stand up to a Level 5 hurricane plus safety factor JUST BARELY.

And let's add the corillary... for tens of billions of dollars less.

john smith wrote:

A good engineer can build a levy that will stand up to a Level 5
hurricane plus safety factor. An EXCELLENT engineer can build a levy
that will stand up to a Level 5 hurricane plus safety factor JUST BARELY.

And let's add the corillary... for tens of billions of dollars less.

And lets build a Level3 instead and pocket the difference for artsee
projects...

Darrel Toepfer wrote:

And lets build a Level3 instead and pocket the difference for artsee
projects...

And let's just drive the pilings 1/3 the way down and pocket the difference.

George Patterson
Coffee is only a way of stealing time that should by rights belong to
your slightly older self.

john smith wrote:

Why would you go to the hassle of an active splitter at 1.7 GHz. when it is
not necessary? Remember, a good engineer can build a bridge that will stand
up to maximum design loads plus safety factor. An EXCELLENT engineer can
build a bridge that will stand up to maximum design loads plus safety factor
JUST BARELY.


Oh what the heck!!!
Let's make this real world...
A good engineer can build a levy that will stand up to a Level 5
hurricane plus safety factor. An EXCELLENT engineer can build a levy
that will stand up to a Level 5 hurricane plus safety factor JUST BARELY.

And let's add the corillary... for tens of billions of dollars less.

The real world is that the politicans controlling the money won't
approve enough for either.


Matt

john smith wrote:

Why would you go to the hassle of an active splitter at 1.7 GHz. when it is
not necessary? Remember, a good engineer can build a bridge that will stand
up to maximum design loads plus safety factor. An EXCELLENT engineer can
build a bridge that will stand up to maximum design loads plus safety factor
JUST BARELY.


Oh what the heck!!!
Let's make this real world...
A good engineer can build a levy that will stand up to a Level 5
hurricane plus safety factor. An EXCELLENT engineer can build a levy
that will stand up to a Level 5 hurricane plus safety factor JUST BARELY.

And let's add the corillary... for tens of billions of dollars less.

Don't forget about the explosives to make them fail at the right time.

john smith writes:

Let's make this real world...
A good engineer can build a levy that will stand up to a Level 5
hurricane plus safety factor. An EXCELLENT engineer can build a levy
that will stand up to a Level 5 hurricane plus safety factor JUST BARELY.


Not quite... See, Level 5, unlike those below it, has no upper limit...

--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

{Splitting a GPS Antenna}

I'll say the same thing I said comm/nav antennas.

You'd adding to your single point of failures. If GPS is important
to you; get separate antennas..

--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433