<div dir="ltr"><div>A friend and I did a bunch of research on this several years ago and our conclusion was that the best single frequency antenna which we could build ourselves was the "shorted annular patch" design. (SAP) <br>
<br>See <a href="http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.180.3985&rep=rep1&type=pdf">http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.180.3985&rep=rep1&type=pdf</a><br><br>However, it needs a 90 degree hybrid which one needs to design for on the PCB. One should also put an LNA and SAW filter there for out of band signal rejection. <br>
<br>Anybody who knows their way around Eagle or Kicad should be able to make one, but its not a good project for a beginner. An alternative which can work well for multi-constellation use is a two or four arm archimedian spiral, logarithmic spiral or "pinwheel" style antenna. (as in Novatel antennas) The #1 consideration is keeping the phase center of the antenna in the exact same place for different frequencies which means four arms are better than two and the antenna should be perfectly flat. (it needs to be a PCB) All of the four arm antennas need a 90 degree hybrid for phasing.<br>
<br></div><div>Building our own antennas at that stage seemed to be more trouble than it was worth at that moment but its still something which I would like to explore. <br><br>The SAP looks like a very good single frequency antenna. <br>
<br>Multiconstellation use - good performance on multiple frequencies with the same phase center is much more of an engineering challenge. I just have a GPS L1 only receiver so for now I've been using and have had fairly good results with a quadrifilar helix timing antenna made by PCTEL (also sold by Lucent) <br>
<br>Its the sixth in Professor Takasu's list of antennas linked from his home page. <a href="http://gpspp.sakura.ne.jp/anteva/anteva.htm">http://gpspp.sakura.ne.jp/anteva/anteva.htm</a><br><br>These specific antennas are often available on ebay for around $30-40, sometimes less (I got one for $22 plus $9 shipping). They look like a gnomes' hat, they are conical.<br>
</div><br>The article is in Japanese but its very much worth translating and reading.<br></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Tue, Mar 11, 2014 at 1:52 AM, mazahirp <span dir="ltr"><<a href="mailto:mazahir.poonawalla@gmail.com" target="_blank">mazahir.poonawalla@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi All,<br>
<br>
Can anyone help me to buy a good antenna which can give me accurate results.<br>
I am using u-blox 6T as receiver and RTKLIB.<br>
Currently I am using GILSON GPS active antenna on both the receivers (base<br>
and rover). I am not an expert into antennas so I wanted to know if this<br>
antenna is good enough? If not, which one should I go for. My budget is<br>
around $100.<br>
<br>
Thanks for the help.<br>
<br>
Cheers,<br>
Max<br>
<br>
<br>
<br>
--<br>
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