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Custom GPS antenna for THL W8 Beyond

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By veepe, Junior Member on 27th August 2013, 01:38 AM
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Hey

I'd like to fix my crappy GPS antenna, can anyone here help me with that - I don't know how it looks like and don't know how to take the phone apart safely besides being careful not to yank the mic
Will only copper wire work?
Has anyone ever done this?
This device is notorious for it's bad GPS reception but there's not info on how to fix it and I'd sure appreciate any help.

Thanks in advance!
 
 
21st September 2013, 12:47 PM |#2  
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Software?
Hey, did you try some software changes, before you unassembly phone? I have an iOcean X7 Elite (same MTK chipset) and Uncletools with updated EPO was helpfull for me. Fix GPS max. 20 seconds. With serial antenna. Check XDA forum or google about GPS fix MTK chipset or tell me, I can write a fast manual how to do that...
24th September 2013, 02:24 PM |#3  
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i managed to make a new GPS antenna. i took a copper adhesive and made a copy of the original one.
now i get a fix but SNR is around 35.
then i closed the back cover and got 30 SNR.
so i put another 2 slice of copper (9cm long) on the cover (one is touching the GPS antenna) and now i got 35 SNR.
but it is not enough. we need around 40-42 snr with 1-2 satellites in order to navigate in the city.

can anyone post a new GPS antenna mod that we can use with a copper adhesive?
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25th September 2013, 09:24 PM |#4  
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You are probably best off finding a microstrip "patch" antenna optimized for
one of the two main GPS frequencies 1.57542 GHz (L1) and 1.2276 GHz (L2).
You could also attempt to build one, like you did, but with optimized
dimensions. These could be very small, on the size of a penny.

THIS is the basics of Microstrip (Patch) Antennas. You should definitely
try that design first! However, I don't know the impedance (the length of W
in the figure below) needed for your device, so you'll have to do some
trial-and-error...

Within THIS rather technical document, there are several simple designs that
you may try to make with your copper-tape-strips.

Finally try Google "homemade DIY gps patch antenna".

Let us know how it goes!



Here are some ideas:






Or perhaps this one?

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27th September 2013, 09:55 AM |#5  
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Quote:
Originally Posted by E:V:A

You are probably best off finding a microstrip "patch" antenna optimized for
one of the two main GPS frequencies 1.57542 GHz (L1) and 1.2276 GHz (L2).
You could also attempt to build one, like you did, but with optimized
dimensions. These could be very small, on the size of a penny.

THIS is the basics of Microstrip (Patch) Antennas. You should definitely
try that design first! However, I don't know the impedance (the length of W
in the figure below) needed for your device, so you'll have to do some
trial-and-error...

Within THIS rather technical document, there are several simple designs that
you may try to make with your copper-tape-strips.

Finally try Google "homemade DIY gps patch antenna".

Let us know how it goes!



Here are some ideas:






Or perhaps this one?

I added 10/15 points just with this

i hope to be helpful to you
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28th September 2013, 05:59 AM |#6  
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i already tried the microstrip gps antenna. it gives great results but when you close the cover... poor results!
28th September 2013, 11:52 AM |#7  
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Quote:
Originally Posted by chenrp

i already tried the microstrip gps antenna. it gives great results but when you close the cover... poor results!

If that is the case, you're probably doing something right!

The cover itself changes the properties of the antenna, usually they compensate this with a velocity factor. What happens, is that the antenna seem larger than it should be, when the cover is closed. Try to compensate by reducing your micro-strip dimensions by multiplying them with ~0.97. Microstrip and patch antennas have a very narrow band-width... (You'll have to be accurate to the mm.) Also make sure the antenna is not touching anything inside, when the cover is closed, as that would again change the properties.
28th September 2013, 11:40 PM |#8  
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GPS antennas...
Quote:
Originally Posted by E:V:A

If that is the case, you're probably doing something right!

The cover itself changes the properties of the antenna, usually they compensate this with a velocity factor. What happens, is that the antenna seem larger than it should be, when the cover is closed. Try to compensate by reducing your micro-strip dimensions by multiplying them with ~0.97. Microstrip and patch antennas have a very narrow band-width... (You'll have to be accurate to the mm.) Also make sure the antenna is not touching anything inside, when the cover is closed, as that would again change the properties.

I have three, two are active devices, with the receiver attached beneath, and require +3 VDC supply and RS-232 for data.
One is a ceramic patch from O.E.M Garmin, as supplied in their hand held units,
The third, is a patch used by old Garmin Flight navigator unit I used in my B-55 Baron. Its dimensions are 2-3/8" on a side, soI doubt you could fit this inside without difficulty, let alone altering the dielectric constant of the board.

But if you have a sizable space between the cover and the main board, you may be able to fit a small ceramic patch antenna that should work nicely, IF the feed impedances are similar.
he enclosed pics should give you a starting point though..
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29th September 2013, 07:48 AM |#9  
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i managed to get 43 SNR! inside my house near the window.(with one stripe connected directly to the antenna contacts)
but i cant fit it inside the phone and still get above 35 SNR.
29th September 2013, 03:26 PM |#10  
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Quote:
Originally Posted by befano71

I added 10/15 points just with this
i hope to be helpful to you

Quote:
Originally Posted by chenrp

i managed to get 43 SNR! inside my house near the window.(with one stripe connected directly to the antenna contacts)
but i cant fit it inside the phone and still get above 35 SNR.

It's pointless to tell us what you get without also telling us what you did or have!
Please post the exact measurements.
29th September 2013, 03:52 PM |#11  
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Quote:
Originally Posted by E:V:A

It's pointless to tell us what you get without also telling us what you did or have!
Please post the exact measurements.

"but i cant fit it inside the phone and still get above 35 SNR."!
pointless to write how i did it if i cant put the antenna inside the phone!
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