Custom GPS antenna for THL W8 Beyond

[veepe]

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!

 

[Florentpraha]

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...

 

[chenrp]

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?

 

[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?

 

[befano71]

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

 

[chenrp]

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

 

[E:V:A]

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.

 

[AECRADIO]

GPS antennas...

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..

 

[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.

 

[E:V:A]

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

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.

 

[chenrp]

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!

 

[befano71]

I posted a picture.
Try doing as I did.
2mm aluminium tape 7cm long attached inside the cover like showed in the photo.
no need to dissassemble or cut or disconnect.
It seems wierd bit it worked for me and other w8s owners

 

[chenrp]

connection to the antenna:
i disconnected the original antenna. taped an adhesive copper film to the antenna contact(in the board).
the film is very short, just enough to touch the back cover.

antenna:
on the back cover, i added adhesive copper antenna.


that way, we have a long antenna (should be ~9cm long) and is far enough from the phone so get better SNR.

see picture.

 

[AECRADIO]

GPS foil antenna.

connection to the antenna:
i disconnected the original antenna. taped an adhesive copper film to the antenna contact(in the board).
the film is very short, just enough to touch the back cover.

antenna:
on the back cover, i added adhesive copper antenna.


that way, we have a long antenna (should be ~9cm long) and is far enough from the phone so get better SNR.

see picture.

You can use stained glass copper foil, they make several different varieties, and most have an adhesive backing, as well as natural copper and black oxide, but the black foil does not solder well, so stay with the natural copper for best results.

Did you match the feed impedance to the receiver? You need a proper load to cause the antenna to operate properly, and at 'L' band and higher, this matters even more-so.

Skin effects vary with frequency, and the higher you go, the more effect this has on any RF path, and can kill a receiver's ability to 'hear'.
GPS signals are already weak, and since 99.99% of the nation are not on the high accuracy portion of the 'L band, we are relegated to 1575.42

If anybody would like to attempt this mod, I would be happy to supply the foil, as I use the same material for rebuilding circuits, and have several rolls. Just send appropriate postage and I will send you more than enough to apply this modification to your device.
I guess you can Email me directly, or through XDA.

 

[chenrp]

You can use stained glass copper foil, they make several different varieties, and most have an adhesive backing, as well as natural copper and black oxide, but the black foil does not solder well, so stay with the natural copper for best results.

Did you match the feed impedance to the receiver? You need a proper load to cause the antenna to operate properly, and at 'L' band and higher, this matters even more-so.

Skin effects vary with frequency, and the higher you go, the more effect this has on any RF path, and can kill a receiver's ability to 'hear'.
GPS signals are already weak, and since 99.99% of the nation are not on the high accuracy portion of the 'L band, we are relegated to 1575.42

If anybody would like to attempt this mod, I would be happy to supply the foil, as I use the same material for rebuilding circuits, and have several rolls. Just send appropriate postage and I will send you more than enough to apply this modification to your device.
I guess you can Email me directly, or through XDA.

theory and practice aside!
i calculated and learned about GPS L band and the results are not satisfying at all.
the only thing that really helped is the one i posted.

 

[maorhadad]

i put the iphone 4 antena and it work verry good

after few atempt to assembly my own antena without success i put the iphone 4 antena .
i get to 38 snr sometimes

 

[befano71]

this is what i have in a almost stormy day almost sea height with the help of the little alluminium strip.
just have to cut an adhesive aluminium tape, 2x70 mm and stick in in the back cover as shown in the picture.
put the cover back on and u'll see the sat levels growing 10-15% more than before.

 

[chenrp]

after few atempt to assembly my own antena without success i put the iphone 4 antena .
i get to 38 snr sometimes

have you connected the iphone's antenna to yours? is there any connection there?

 

[maorhadad]

have you connected the iphone's antenna to yours? is there any connection there?

Not my brother.
Just peeled the metal band that in the back of the iPhone 4, and stuck it in the back of my bewond W8 as seen in the picture.

before i did it id do that guide :

thlmobilestore.com/news/gps-fix

It helps a little but not enough.
After I stuck the antenna of the iPhone 4 that comes a high precision level and not lose reception when I move for a second under a bridge or something like that ....

 

[cacan031]

Custom GPS tAntenna

Used kitchen aluminium foil, as befano71 suggested ["2mm aluminium tape 7cm long attached inside the cover like showed in the photo"]. Built in a hurry, and might not be with perfect measures, but these are results on a foggy, cloudy evening (I was leaning through a window of a building, hence some satellites are zeroed). GPS fix in <10sec ...

Custom made aluminium foil GPS antenna for THL W8S:

Before mod:

After mod: