Re: [time-nuts] Difference in GPS antennas
My Panasonic VIC100 antenna had a few screws to hold the bottom to the
plastic cone top. The bottom had an o-ring seal that stuck a little
but was still pretty easy to slide the bottom from the top half.
Inside was a patch antenna on top of a pcb.
Thanks. I tried again and it came apart easily. There is an O-ring but no
glue. (I wonder why I didn't get it the first try.)
The antenna isn't a patch. (Or I don't recognize it as such.)
It's a cylinder, 2 inches tall, 3/4 inch in dia, sticking up over a 2 inch
square PCB that's screwed into an aluminum base place.
It's made of flexible PCB material wrapped around to make a cylinder. The
outside bottom 3/4 inch is a plane. There is an obvious solder joint line
closing the plane. The inside top has 4 fingers spiraling around at 45
degrees. The lower inside part (opposite the plane) has some wiggles in some
traces, but I haven't figured out the equivalent circuit.
--
These are my opinions, not necessarily my employer's. I hate spam.
Hal Murray wrote:
My Panasonic VIC100 antenna had a few screws to hold the bottom to the
plastic cone top. The bottom had an o-ring seal that stuck a little
but was still pretty easy to slide the bottom from the top half.
Inside was a patch antenna on top of a pcb.
Thanks. I tried again and it came apart easily. There is an O-ring but no
glue. (I wonder why I didn't get it the first try.)
The antenna isn't a patch. (Or I don't recognize it as such.)
It's a cylinder, 2 inches tall, 3/4 inch in dia, sticking up over a 2 inch
square PCB that's screwed into an aluminum base place.
It's made of flexible PCB material wrapped around to make a cylinder. The
outside bottom 3/4 inch is a plane. There is an obvious solder joint line
closing the plane. The inside top has 4 fingers spiraling around at 45
degrees. The lower inside part (opposite the plane) has some wiggles in some
traces, but I haven't figured out the equivalent circuit.
Thats a quadrifilar helix antenna.
bruce
Hi Hal,
Can you take some photographs ? It would be intersting to see it. It sounds
like some dipoles with phasing lines under them possibly.
thanks,
Bill....WB6BNQ
Hal Murray wrote:
My Panasonic VIC100 antenna had a few screws to hold the bottom to the
plastic cone top. The bottom had an o-ring seal that stuck a little
but was still pretty easy to slide the bottom from the top half.
Inside was a patch antenna on top of a pcb.
Thanks. I tried again and it came apart easily. There is an O-ring but no
glue. (I wonder why I didn't get it the first try.)
The antenna isn't a patch. (Or I don't recognize it as such.)
It's a cylinder, 2 inches tall, 3/4 inch in dia, sticking up over a 2 inch
square PCB that's screwed into an aluminum base place.
It's made of flexible PCB material wrapped around to make a cylinder. The
outside bottom 3/4 inch is a plane. There is an obvious solder joint line
closing the plane. The inside top has 4 fingers spiraling around at 45
degrees. The lower inside part (opposite the plane) has some wiggles in some
traces, but I haven't figured out the equivalent circuit.
--
These are my opinions, not necessarily my employer's. I hate spam.
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On Fri, Aug 14, 2009 at 08:03:58PM -0700, Hal Murray wrote:
My Panasonic VIC100 antenna had a few screws to hold the bottom to the
plastic cone top. The bottom had an o-ring seal that stuck a little
but was still pretty easy to slide the bottom from the top half.
Inside was a patch antenna on top of a pcb.
Thanks. I tried again and it came apart easily. There is an O-ring but no
glue. (I wonder why I didn't get it the first try.)
The antenna isn't a patch. (Or I don't recognize it as such.)
It's a cylinder, 2 inches tall, 3/4 inch in dia, sticking up over a 2 inch
square PCB that's screwed into an aluminum base place.
It's made of flexible PCB material wrapped around to make a cylinder. The
outside bottom 3/4 inch is a plane. There is an obvious solder joint line
closing the plane. The inside top has 4 fingers spiraling around at 45
degrees. The lower inside part (opposite the plane) has some wiggles in some
traces, but I haven't figured out the equivalent circuit.
Quadrafiler helix... feed for it with matching networks, combiner and
phasing delays in microstrip.
--
Dave Emery N1PRE/AE, die@dieconsulting.com DIE Consulting, Weston, Mass 02493
"An empty zombie mind with a forlorn barely readable weatherbeaten
'For Rent' sign still vainly flapping outside on the weed encrusted pole - in
celebration of what could have been, but wasn't and is not to be now either."
Bruce Griffiths wrote:
Hal Murray wrote:
My Panasonic VIC100 antenna had a few screws to hold the bottom to the
plastic cone top. The bottom had an o-ring seal that stuck a little
but was still pretty easy to slide the bottom from the top half.
Inside was a patch antenna on top of a pcb.
Thanks. I tried again and it came apart easily. There is an O-ring but no
glue. (I wonder why I didn't get it the first try.)
The antenna isn't a patch. (Or I don't recognize it as such.)
It's a cylinder, 2 inches tall, 3/4 inch in dia, sticking up over a 2 inch
square PCB that's screwed into an aluminum base place.
It's made of flexible PCB material wrapped around to make a cylinder. The
outside bottom 3/4 inch is a plane. There is an obvious solder joint line
closing the plane. The inside top has 4 fingers spiraling around at 45
degrees. The lower inside part (opposite the plane) has some wiggles in some
traces, but I haven't figured out the equivalent circuit.
Thats a quadrifilar helix antenna.
A quite traditional antenna form.
Not sure I have one of those around here.
Cheers,
Magnus
On 8/15/09 7:58 AM, "Magnus Danielson" magnus@rubidium.dyndns.org wrote:
Thats a quadrifilar helix antenna.
A quite traditional antenna form.
Not sure I have one of those around here.
If you're near a harbor with fishing boats, you'll see plenty of quad
helices about a half a meter in overall height, used for VHF Weather
satellite reception. They're also used on spacecraft (Mars Science Lander,
Mars Reconnaissance Orbiter, and Phoenix all have UHF quad helix antennas, I
think, for about 400 MHz)
The 4 helices need to be fed in the appropriate phase (0,90,180,270),
usually, they're fed in pairs (a differential signal feeds 0,180 and another
feeds 90/270)
There are several ways to phase them, depending on the bandwidth
requirements. A quadrature hybrid is one way. The other is to make one helix
slightly longer than resonant and the other slightly shorter.
Lux, Jim (337C) wrote:
On 8/15/09 7:58 AM, "Magnus Danielson" magnus@rubidium.dyndns.org wrote:
Thats a quadrifilar helix antenna.
A quite traditional antenna form.
Not sure I have one of those around here.
If you're near a harbor with fishing boats, you'll see plenty of quad
helices about a half a meter in overall height, used for VHF Weather
satellite reception. They're also used on spacecraft (Mars Science Lander,
Mars Reconnaissance Orbiter, and Phoenix all have UHF quad helix antennas, I
think, for about 400 MHz)
Not used by the fishing vesels near me...
I didn't mean helixantennas as such, I was just asking myself the
question if any of my GPS antennas was infact of the quadra-helix
design, a few of them have the sizes that they could be that.
The 4 helices need to be fed in the appropriate phase (0,90,180,270),
usually, they're fed in pairs (a differential signal feeds 0,180 and another
feeds 90/270)
There are several ways to phase them, depending on the bandwidth
requirements. A quadrature hybrid is one way. The other is to make one helix
slightly longer than resonant and the other slightly shorter.
A typical GPS sat has two rings of helix antennas, an inner and outer
ring. These create a far-distance shape of lobes that i circularly
fairly even but pushes more energy towards the edge of the earth, as
seen from the satellite, such that the additional space loss from
increased distance is being somewhat equalized by the GPS antenna.
That's the trick being used to reduce the power variations from the GPS
sats as experienced by the user.
Cheers,
Magnus
On 8/15/09 8:27 AM, "Magnus Danielson" magnus@rubidium.dyndns.org wrote:
If you're near a harbor with fishing boats, you'll see plenty of quad
helices about a half a meter in overall height, used for VHF Weather
satellite reception. They're also used on spacecraft (Mars Science Lander,
Mars Reconnaissance Orbiter, and Phoenix all have UHF quad helix antennas, I
think, for about 400 MHz)
Not used by the fishing vesels near me...
Really? Practically all the fishing boats (mostly squid) boats going out
from Ventura Harbor (in Southern California) have big ol' quad helix
antennas up on the cross bar (as well as the usual HF SSB and VHF whips and
the radar). Maybe it's a regional preference thing (or folks are going to
the 1.6 GHz band or something).
I didn't mean helixantennas as such, I was just asking myself the
question if any of my GPS antennas was infact of the quadra-helix
design, a few of them have the sizes that they could be that.
The one on my handheld Garmin (about 10 years old) is a quad helix. I would
venture that any of the antennas that are about the size of your finger are
a quad helix.
Thinking of other antennas in that form factor (10-15 cm long, more than 1
cm in diameter) maybe Iridium or Globalstar phones use a quad helix?
As I recall, this is the type of antenna my handheld GPSr has. I had a set of batteries bleed out in and had to disassemble it in order to do a good cleaning.
-Dave
----- Original Message -----
From: "Magnus Danielson" magnus@rubidium.dyndns.org
To: "Discussion of precise time and frequency measurement" time-nuts@febo.com
Sent: Saturday, August 15, 2009 9:27:30 AM GMT -07:00 US/Canada Mountain
Subject: Re: [time-nuts] Difference in GPS antennas
Lux, Jim (337C) wrote:
On 8/15/09 7:58 AM, "Magnus Danielson" magnus@rubidium.dyndns.org wrote:
Thats a quadrifilar helix antenna.
A quite traditional antenna form.
Not sure I have one of those around here.
If you're near a harbor with fishing boats, you'll see plenty of quad
helices about a half a meter in overall height, used for VHF Weather
satellite reception. They're also used on spacecraft (Mars Science Lander,
Mars Reconnaissance Orbiter, and Phoenix all have UHF quad helix antennas, I
think, for about 400 MHz)
Not used by the fishing vesels near me...
I didn't mean helixantennas as such, I was just asking myself the
question if any of my GPS antennas was infact of the quadra-helix
design, a few of them have the sizes that they could be that.
The 4 helices need to be fed in the appropriate phase (0,90,180,270),
usually, they're fed in pairs (a differential signal feeds 0,180 and another
feeds 90/270)
There are several ways to phase them, depending on the bandwidth
requirements. A quadrature hybrid is one way. The other is to make one helix
slightly longer than resonant and the other slightly shorter.
A typical GPS sat has two rings of helix antennas, an inner and outer
ring. These create a far-distance shape of lobes that i circularly
fairly even but pushes more energy towards the edge of the earth, as
seen from the satellite, such that the additional space loss from
increased distance is being somewhat equalized by the GPS antenna.
That's the trick being used to reduce the power variations from the GPS
sats as experienced by the user.
Cheers,
Magnus
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Lux, Jim (337C) wrote:
On 8/15/09 8:27 AM, "Magnus Danielson" magnus@rubidium.dyndns.org wrote:
If you're near a harbor with fishing boats, you'll see plenty of quad
helices about a half a meter in overall height, used for VHF Weather
satellite reception. They're also used on spacecraft (Mars Science Lander,
Mars Reconnaissance Orbiter, and Phoenix all have UHF quad helix antennas, I
think, for about 400 MHz)
Not used by the fishing vesels near me...
Really? Practically all the fishing boats (mostly squid) boats going out
from Ventura Harbor (in Southern California) have big ol' quad helix
antennas up on the cross bar (as well as the usual HF SSB and VHF whips and
the radar). Maybe it's a regional preference thing (or folks are going to
the 1.6 GHz band or something).
Haven't all of the VHF weather satellites been decommissioned?
-Chuck Harris