Is it possible to use small PCB as GPS antenna for testing?

[davorin]

GPS antenna

Is it possible to use a small PCB as GPS antenna for testing?

Any good reference how they layout should look like if it is possible?

 

[pisoiu]

Re: GPS antenna

Hi,
Basically all GPS active antennas are made with a ceramic based antenna installed near the LNA, to minimise losses. The ceramic material on which antenna is made is a relatively high quality material for RF frequencies, and is far better than a regular FR4 for example. Also, its thickness and homogenity is important if you want to achieve good signal. Also, a special care must be taken for LNA. I tried to replace the ceramic antenna inside a GPS active antenna with a piece of ITO film, but it didn't worked. My advice: use a standard active antenna, even for testings, it is not so expensive.

/pisoiu

 

[Debeli]

Re: GPS antenna

Simple rectangular patch can do well. Designed with microstrip feeding and adequate LNA (not more than 2 dB NF) it is good enough for testing purposes.

I have wrote "p@tch" instead of "fix". Thanks to automatic software piracy detection at the forum, this is automatically translated.
Naturally that active integrated antenna is the best solution. Usualy you can expect up to 40 dB gain and 1-1.5 dB NF with such modules. But, if you wanna play, try the p@tch.


Regards
D.


Edited by makswell.

 

[plasma]

Re: GPS antenna

Hi davorin

here an application note that can help you
to build your test antenna.

pl

 

[mamali]

Re: GPS antenna

Hi,
Basically all GPS active antennas are made with a ceramic based antenna installed near the LNA, to minimise losses. The ceramic material on which antenna is made is a relatively high quality material for RF frequencies, and is far better than a regular FR4 for example. Also, its thickness and homogenity is important if you want to achieve good signal. Also, a special care must be taken for LNA. I tried to replace the ceramic antenna inside a GPS active antenna with a piece of ITO film, but it didn't worked. My advice: use a standard active antenna, even for testings, it is not so expensive.
/pisoiu

whats the meaning of ceramic based antenna? you mean a p@tch antenna with ceramic substrate? or a dielectric resonator antenna?
in both cases, you should take care of antenna parameters, it is so sensitive to er of the material, if you explain better the antenna, i will help more, i had work in both kinds of antenna.

btw, becouse i ITO film u sed, i thought it was a dielectric resonator antenna, am i right?

marti

 

[pisoiu]

Re: GPS antenna

I mean patch antenna with ceramic substrate. Those types which are very common in gps antennas around many manufacturers. I tried to replace the antenna with a piece of conductive ITO film because this film is easier to install on a windshield of the car for example and it is not visible, but ..obviously...it didn't work. As you said, the parameters of the ceramic material are important to achieve a good signal.

/pisoiu

 

[mamali]

Re: GPS antenna

I mean fix antenna with ceramic substrate. Those types which are very common in gps antennas around many manufacturers. I tried to replace the antenna with a piece of conductive ITO film because this film is easier to install on a windshield of the car for example and it is not visible, but ..obviously...it didn't work. As you said, the parameters of the ceramic material are important to achieve a good signal.
/pisoiu

well, if it is a simple rectangular mic. p@tch antenna, printed on a ceramic, then the dimentions of p@ch is directly connected to er of the substrate. ceramics have bigest er in subs (around 20 and more, 20 is typical for GPS antennas), thus you can not use same p@tch with a lower er substrate, as ITO film (do you know its er?). becouse of lower er of ITO, you should use a bigger p@tch, wich may not be practical {you should change the dimentions of patch as this : a(new)=a(old)*sqrt(er(old)/er(new))}. for example, if er(ceramic)=20 and er(ITO)=4, then:
a(new)=a(old)*2.23; which i think is not practical. however, there are a lot of technics to minaturize the p@tch (other than using high er substrates), and, you should now that lower er = wider bandwidth.
bytheway, if you specify the design better, and if you are interested!, i will help more.

marti

 

[pisoiu]

Re: GPS antenna

Marti, thanks for the offer, but this idea with ITO was some time ago, and I knew from the beginning there are low chances to work. But for 5 minutes work, it worth to try. The best sollution (as I said in the first reply, to davorin) is to use a standard GPS antenna. Not very expensive, and the time to market is short.

/pisoiu

 

[mamali]

Re: GPS antenna

Marti, thanks for the offer, but this idea with ITO was some time ago, and I knew from the beginning there are low chances to work. But for 5 minutes work, it worth to try. The best sollution (as I said in the first reply, to davorin) is to use a standard GPS antenna. Not very expensive, and the time to market is short.

/pisoiu

dear pisoiu,
thats ok, bytheway, i am working on two-segment rectangular dielectric resonator antennas, and minaturized fractal patch antennas, and i have some papers on these topics (with other guys although ), and becouse of very narrow-band reqierement of GPS antennas, i want to know if this new kind of antennas could be used there; and i am looking for someone who has experience with it. so, if you are interested, i want to know the specification needed for GPS antennas, and its limitations that should be taken care in design process, such as space limitation and gain.
well, please tell me if you (and/or other buddies ) are interested in that, and i will tell you more about these cool new antennas more.

rgrds, marti

 

[billano786]

Re: GPS antenna

A friend of mine as a commercial application that requires an active GPS antenna. If any one of you is intrested in selling it around $2.5 dollars, he can buy in multiples of 1000 pcs.

 

[mamali]

Re: GPS antenna

A friend of mine as a commercial application that requires an active GPS antenna. If any one of you is intrested in selling it around $2.5 dollars, he can buy in multiples of 1000 pcs.

well, what is design specification? space limits? and 2.5$ per manufactured antenna? could you post more informations about please?

rgrds, marti

 

[mamali]

Re: GPS antenna

Is it possible to use a small PCB as GPS antenna for testing?

Any good reference how they layout should look like if it is possible?

if you mean Printed Circuit Board by PCB (which i think you do!), i should tell you that Microstrip Antennas are actually PCBs, becouse they are printed on substrates. but there is some considerations.
1. simple printed antennas (such as edge fed p@tches) have very low band-width (say, 0.3%~ 2.5% with VSWR<2), but becouse of narrowband requirements of normal GPS antennas, i think they are practiacl.
2. usual RF substrates have high er to miniaturize the size of circuite. these high permittivity subs could be also used for p@tchs, and make it minature too, but consecuently a narrower band-width is gained.
3. better charasteristics could be reached by probe-fed p@tches, but manufacturing is then harder.
4. airgaps and very-low permittivity subs (such as foams) could be used to wide-banding the antenna, but a bigger p@tch is achieved (for example, as a 1.6GHz antenna, p@tch dimentiones will be about : 9.5cmx9.5cm), which is offen not practical.
5. miniaturization methods could be used to gain smaller p@tches (include loading with notches and lumped-elements). fractal miniaturized patches could be also practical.
6. due to Circular Polarization of many GPS antennas, some especial designs is proved to have better performance, such as square p@tchs or circular patches. here the main parameter which limit the bandwidth of the antenna is Axial-Ratio. typically 1% bandwidth could be achived with usual simple p@tchs.
7. as you know, most of these antennas are attached to an active RF section (may called active antennas), and thus higher VSWR is acceptable. having count this, a more miniaturized p@tches (with high er subs) could be used.
8. and finally, the p@tch antennas are not the only choice. one of my friends haa a very keen idea on merging RF parts with dielectric resonator antennas. if anybody interested in, please be free to pm me about.

hope be helpfull all these ,
cheers, marti

 

[Jackwang]

GPS antenna

hello, I am trying me best to complete a GPS receivers.
I need an antenna array, but I don't know how to design it? I want to know the method that design the array antenna with microstrip?
can you have good ideas? pl tell me！

 

[artem]

GPS antenna

simple antenna link :

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