2 Antenna Comparisons With Netstumbler

greenwise · 09-17-2004

Hello,

Could someone help explain this graph that compares my homemade antenna and the one I purchased http://www.greenwise.ca/compare-antennas.gif?

Every antenna that I have built produces the irratic lines at the top of the graph. Otherwise, of the 2 that you see in the graph, my homemade one seems to be performing just as well as the one I purchased.

The antenna I tried to copy is a 14dbi directional antenna that I bought from HDcom. Instead of using a PCB to make my version of the antenna, I used sheetmetal and 14ga copper wire. Otherwise all measurements are exactly the same.

Thanks in advance for your help.

Greenwise

wrzwaldo · 09-17-2004

Yes the graph shows that your antenna is not as good as the one you purchased. How about some pics of the two antennas? Also would have been nice to see the scale to the left (sure wish it was stationary).

greenwise · 09-18-2004

http://www.greenwise.ca/antenna1.gif
http://www.greenwise.ca/antenna2.gif

rfmw · 09-18-2004

When you compare two antennas be sure that each antenna has just the same circumstances as the other (position, rotation, height, ... and of course the objects close to antenna, ....).

And the most important thing is that you don't have multipath propagation, which surely occurs indoors...

anode · 09-18-2004

I bought a Hawkins Omni and a directional. I made a porabalic reflector for the Omni. (just a folder with tin foil spray mounted to it and foam core to give it the curve) I get a much better signal with the omni and reflector then with the directional (as-is)
Just food for thought.

As for your antenna, I'd make the length of the wire conecting the discs the same. Keep it even as possible.

(the galvo strikes me as not the stuff to use, but have *no* reason why. just tookme by surprise I guess)

09-17-2004	#1 (permalink)
greenwise Registered Member Join Date: Sep 2004 Posts: 3	2 Antenna Comparisons With Netstumbler Hello, Could someone help explain this graph that compares my homemade antenna and the one I purchased http://www.greenwise.ca/compare-antennas.gif? Every antenna that I have built produces the irratic lines at the top of the graph. Otherwise, of the 2 that you see in the graph, my homemade one seems to be performing just as well as the one I purchased. The antenna I tried to copy is a 14dbi directional antenna that I bought from HDcom. Instead of using a PCB to make my version of the antenna, I used sheetmetal and 14ga copper wire. Otherwise all measurements are exactly the same. Thanks in advance for your help. Greenwise

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09-17-2004	#2 (permalink)
wrzwaldo I amuse you? Join Date: Dec 2003 Posts: 9,147	Yes the graph shows that your antenna is not as good as the one you purchased. How about some pics of the two antennas? Also would have been nice to see the scale to the left (sure wish it was stationary).

09-18-2004	#3 (permalink)
greenwise Registered Member Join Date: Sep 2004 Posts: 3	http://www.greenwise.ca/antenna1.gif http://www.greenwise.ca/antenna2.gif

09-18-2004	#4 (permalink)
rfmw Registered Member Join Date: Aug 2004 Posts: 15	When you compare two antennas be sure that each antenna has just the same circumstances as the other (position, rotation, height, ... and of course the objects close to antenna, ....). And the most important thing is that you don't have multipath propagation, which surely occurs indoors...

09-18-2004	#5 (permalink)
anode Registered Member Join Date: Sep 2004 Posts: 2	I bought a Hawkins Omni and a directional. I made a porabalic reflector for the Omni. (just a folder with tin foil spray mounted to it and foam core to give it the curve) I get a much better signal with the omni and reflector then with the directional (as-is) Just food for thought. As for your antenna, I'd make the length of the wire conecting the discs the same. Keep it even as possible. (the galvo strikes me as not the stuff to use, but have no reason why. just tookme by surprise I guess)