Hi Jerry:
The Trimble is the oldest mass produced GPS receiver I know of and because the early receivers used high gain antennas
it seems that Trimble kept that idea for the newer designs. They like about 41 dB gain between the antenna and the input
to the receiver.
http://www.prc68.com/I/Trimpack.shtml#Ant
Newer designs probably place that gain in the front end rather than at the antenna. But having around 20 dB of gain at
the antenna gretly decreases the effect of feed line loss on noise figure.
--
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
-------- Original Message --------
Due to access problems, I run my Thunderbolt with a Symmetricom 58532A
antenna placed indoor near a window facing South
cant get much worse but
most of the time it will be locked onto 3 or 4 satellites. I recently
bought a www.leobodnar.com <http://www.leobodnar.com> GPSDO for my SDR ham
radio setup. I was very surprised to find that this minimalist GPSDO using
a small patch antenna with internal LNA placed near my window had satellite
& PPL lock within a few seconds. It requires 3-4 satellite locks for its
PPL. However, when I attached the patch antenna to my Thunderbolt
satellite signal strength were zero or minus for all satellites. The specs
for the patch antenna are listed below.
I would appreciate any advice understanding this behavior.
Jerry NY2KW
Center Frequency 1575.42MHz±3 MHz
V.S.W.R 1.5:1
Band Width ±5 MHz
Impendence 50 ohm
Peak Gain >3dBic Based on 7×7cm ground plane
Gain Coverage >-4dBic at 90°<0<+90°(over 75% Volume)
Polarization RHCP
LNA/Filter
LNA Gain (Without cable) 28+/-3dB
Noise Figure 1.5dB Typ.
Filter Out Band Attenuation (f° =1575.42MHz)
7dB Min f0+/-20MHZ
20dB Min f0+/-50MHZ
30dB Min f0+/-100MHZ
V.S.W.R <2.0
DC Voltage 2.7V/3.0V/3.3V/5.0V/3.0V to 5.0V/other
DC Current 5mA /11mA/15mA Max
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