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        Discussion 2.4 GHz 9 dBi Rubber Duck Antenna omnidirectional

#1 G-unit Oct 12, 2008 09:27 PM

2.4 GHz 9 dBi Rubber Duck Antenna omnidirectional
 
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Hey,
I'm looking for a better omnidirectional Antenna for my Rx,i have a 3-dbi and was looking at this 9-dbi but i don't know if it is any good.I don't understand the RF Antenna Patterns :confused: so can u help me understand this.I have some pics of a 9 ,7 ,5-dbi RF Antenna Patterns can u tell me witch one is best. :D

Thanks G

#2 sokiii Oct 12, 2008 10:16 PM

It's very hard to answer the question "which ... is the best?" Answer depends on what you want (sometimes how much money you have). But I will try.
5dB is the best
7dB and 9dB can give a better range if you mount Rx antenna high and will fly your plane low.
If you need range patch, yagi or parabolic antenna are better choice. Omni directional antennas are good for flying around you.

#3 Gussy Oct 12, 2008 10:23 PM

For FPV, the 5db is the best as it offers the best vertical coverage.

Got any links to these antennas?

#4 G-unit Oct 12, 2008 10:23 PM

Thats just it, i fly about 1/2 to 3/4 of a mile out in all direction and some times 2500 ft high and will go higher

#5 G-unit Oct 12, 2008 10:32 PM

Yes, link http://www.hyperlinktech.com/category.aspx?id=73

#6 Gussy Oct 12, 2008 10:48 PM

If you fly in all directions at low or high altitudes then the 5db would be the best option.

#7 G-unit Oct 12, 2008 10:49 PM

Quote:

Originally Posted by Gussy
If you fly in all directions at low or high altitudes then the 5db would be the best option.


Thanks :D

#8 JMSTECH Oct 13, 2008 03:26 PM

Quote:

Originally Posted by G-unit
Thats just it, i fly about 1/2 to 3/4 of a mile out in all direction and some times 2500 ft high and will go higher

Perhaps go for a 8db patch and mount it on a tiny pocket camera tripod. Having it mounted close to the ground will give you unbelievable reception and I've seen Kilrah do some amazing ranges with this set up which I copied with successful results. :) Spend the money once and spend it wisely or end up like me with a shop full of junk! :p

#9 G-unit Oct 13, 2008 03:36 PM

Hey JMSTECH,
I made a GP patch that i have not tried yet i was going to wait for some long rang tryouts for that but what angel do i point the patch when i have it close to the ground?
Thanks G

#10 JMSTECH Oct 13, 2008 03:45 PM

I tried it straight up, or slightly off from 90 degrees... you should play around with the angles and btw... you have the best flying field so you can afford to experiment with the various angles and not worry about loosing your bird. :D OK.. I'm jealous of you LOL! :D

#11 Adam Neat Oct 13, 2008 03:55 PM

Im a licensed ham, just dont get on the air like I used to. From what I remember about antenna theory when you start increasing the gain on antenna's your effectivly taking the signal away from one part of the radiation pattern and focusing it on another part.

Similar to focusing a light beam.

To help visualise the patterns, for example on the horizontal patterns imagine if you were looking straight down(or up) at your plane. The radiation pattern would be pretty equal in all directions (if your antenna was vertical) in a horizontal pattern.

For the vertical patterns imagine if your aircraft was out on front of you and the radiation pattern would be in the vertical plane, above and below the aircraft.

With a perfect omnidirectional pattern you would end up with something close to a donut shape. Signal emitting equally in all direction.

Seems like for the application here something with a little more of "downward" pattern might get youy a little more range??

#12 Ira NZ Oct 14, 2008 05:57 AM

Is receiving strength and pattern always going to be equivalent to transmitting? Or at least similar?

#13 tvdude310 Oct 14, 2008 02:27 PM

Quote:

Originally Posted by JMSTECH
Perhaps go for a 8db patch and mount it on a tiny pocket camera tripod. Having it mounted close to the ground will give you unbelievable reception and I've seen Kilrah do some amazing ranges with this set up which I copied with successful results. :) Spend the money once and spend it wisely or end up like me with a shop full of junk! :p

How close to the ground is best? Also, with it close to the ground, do you end up with decent reception when you fly low?

#14 c_matt92 Oct 14, 2008 03:12 PM

The beam on the 9dbi omni is a 25 degree beam, which means 12.5 degrees from straight line of the antenna to above the antenna. That means for the plane to be within the best view of the antenna, at 300 feet away from the base station, your altitude could be no more the 66.5 feet (tan(12.5)*300). Now, does that mean that the plane will not be covered? No. It just won't be as good as it could be. The 5 dbi seems to have a beam with of 70 degrees. That means you could fly 173 feet high and still be good.

Now, say we extend this out to half a mile (2640 feet). 9 dbi gives you a ceiling at 586 feet, which should be enough altitude for you, unless you are flying mountain sides. Which is best comes down to where you will be flying. I believe that if you are going for the long range flights, the 9 dbi antenna should serve you fine as you probably wont be flying at the close ranges except for take off and landings, which means you will be flying a little lower.

#15 JMSTECH Oct 14, 2008 04:45 PM

Quote:

Originally Posted by tvdude310
How close to the ground is best? Also, with it close to the ground, do you end up with decent reception when you fly low?

Hey Rob you high end FOX T.V. Network technician... you know the answer to that question LOL!!!! Just for the crowd... the answer is I have it mounted about 2 inches off the ground and the reception on the low flight is not that great but it doesn't matter to me since I'm landing by that time! If you watched some of my later videos you will see the reception great at higher ranges but starts to :pcarp:p out upon landing. :)


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