Eggtimer TRS range/antenna

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taiwanluthiers

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My Eggtimer had poor range... if I'm more than 500ft away it loses signal completely. I'm not sure if I'm using the right antenna or there's something else at play. I'm using a 5db rubber ducky antenna designed for WiFi routers, but since it didn't fit in my AV bay (it's 8" long) I took the rubber cap off and bent the antenna to fit the bay. When I flew the rocket for my L2 attempt I noticed the range was very bad, 500ft at the most. I later discovered I had broken the antenna....

Is there anything else I can try for antenna that can give me greater range?
 
My Eggtimer had poor range... if I'm more than 500ft away it loses signal completely. I'm not sure if I'm using the right antenna or there's something else at play. I'm using a 5db rubber ducky antenna designed for WiFi routers, but since it didn't fit in my AV bay (it's 8" long) I took the rubber cap off and bent the antenna to fit the bay. When I flew the rocket for my L2 attempt I noticed the range was very bad, 500ft at the most. I later discovered I had broken the antenna....

Is there anything else I can try for antenna that can give me greater range?

New antennas... You can get up to 11,000 with the stock antennas and up to 18,000 with the rubber duckie antennas. I'm guessing your using the wrong antennas.
 
So what does frequency range have to do with antenna? I just thought that if I have a 5db 2.4GHz antenna it just becomes a 3 db 900 MHz antenna or something. I can't really fit anything exceedingly long inside the rocket because of space limitation. Is this a function of antenna shape or material?

Would getting a Yagi antenna for the LCD receiver help?
 
Every antenna is tuned for a specific frequency based on wavelength. One made for 2.4ghz will be horrible at receiving 900mhz signals. I have the Linx antenna from the thread in the link I posted. It is only about 4" long. A yagi probably wouldn't work too good, because it is directional, and you would have to actively point it at the rocket. With the Linx antennas, you should be good to at least 15k feet.
 
I am sorry to say this, but if everyone would actually read the user manual we would not have these many Eggfinder threads on the same subject. Cris does an excellent job explaining how the whole system works and recommends what type of antennas and batteries one can use.


To save you the homework, these two should give you great range.
https://www.mouser.com/ProductDetai...16-CW-QW/?qs=sGAEpiMZZMsgSGrx0WqTbFMnk/frcpaA
https://www.mouser.com/ProductDetai...-HWR-RPS/?qs=sGAEpiMZZMsgSGrx0WqTbOhGjOY5qwiN
 
If you're talking about GROUND range and you're not in the middle of nowhere (i.e. a dry desert lake bed), 500' is pretty normal. 900 MHz doesn't propagate well over the ground or through obstructions. If you're only getting 500' IN THE AIR that's a different matter. Try it with the included wire antennas or the aforementioned Linx Technologies ANT-916-CW-QW and -HW antennas, and if it's still bad then send an email to [email protected] and we'll see if we can figure it out.
 
I was getting 500 feet range in my apartment complex, by leaving the device in my room and then I'd go outside until I lose the connection. So I guess considering that it's pretty good...

I had better range in the air, however when the rocket boosted up I lost connection, when it was landing halfway down on drogue/main I was getting good connection (with the bad antenna too) until it landed.
 
I was getting 500 feet range in my apartment complex, by leaving the device in my room and then I'd go outside until I lose the connection. So I guess considering that it's pretty good...

I had better range in the air, however when the rocket boosted up I lost connection, when it was landing halfway down on drogue/main I was getting good connection (with the bad antenna too) until it landed.

It's very typical that you'll lose the fix on boost, the GPS has trouble keeping up when it's moving fast. Depending on how high you went and your antennas, you might get the signal back sometime before apogee, or sometime on the way down. It's also typical to lose the signal right before you land, since as I've mentioned before the ground range is not nearly as good as the air range. As long as you get a fix before landing (which it sounds like you did...) then you should be able to retrieve your rocket, which is the ultimate goal. Better antennas will help both the ground and air range; I know guys that have flown to nearly 20K with the Linx antennas and kept lock all the way through the flight except for a few seconds under boost.
 
If the rocket lands next to a chicken coop (laying eggs) the Eggfinder would live up to its name...
 
Get the right antenna and it will work much better.
Mine had signal for most of the flight and on lost lock for a few seconds.
Good for about a mile or more on the ground.

JD
 
So what does frequency range have to do with antenna? I just thought that if I have a 5db 2.4GHz antenna it just becomes a 3 db 900 MHz antenna or something. I can't really fit anything exceedingly long inside the rocket because of space limitation. Is this a function of antenna shape or material?

Would getting a Yagi antenna for the LCD receiver help?
To transmit power, an antenna need to resonate (be tuned) to the transmitter frequency. For example f = 1 GhZ = 1,000,000,000 HZ = 1 x 10^9 Hz. Radio wave travel at the speed of light with is c = 3 x 10^10 cm/s = 30 x 10^9 cm/s. The wavelength is wl = c/f = 30 x 10^9 cm/s /1 x 10^9 /s= 30 cm.

The simplest antenna is a 1/4 wavelength so a 1/4 wave @ 1 GHz = 30 cm/4 = 7.5 cm = 3". This is the electrical length. The physical length could be short is the wire is coiled as some rubber duckies are, but when the physical length = the electrical length you get the best performance.

So a 1/4 wave 900 Mhz band antenna (900-930 Mhz) will be ~7.5/.915 = 8.2 cm long and a 2.4 GHz band antenna (2.4-2.6 GHz) will be ~30/2.5 = 3 cm long.


A 1/4 antenna is an omnidirectional antenna having approximately the same signal strength in all directions. If you make the antenna longer in 1/4 wave increments (simple antennas) it will become more directional. In microwave frequencies we tend to use flat panel (patch) antennas to get directionality and gain.

https://www.l-com.com/wireless-antenna-900-mhz-antennas

https://www.l-com.com/wireless-antenna-24-ghz-wifi-antennas https://www.l-com.com/wireless-antenna-24-ghz-patch-antennas

Without going into detail and 8 db patch antenna on the receiver will greatly increase the reception range. https://www.l-com.com/wireless-antenna-24-ghz-8-dbi-flat-patch-antenna If you mount the antenna horizontally on a tripod, the coverage will be a 35 degree half angle overhead cone. Increasing the signal strength by 6 db doubles the range, by 12 db quadrupoles the range. As an antenna gain goes up the solid ange (collection volume) decrease proportionally so more agin only helps if you track you rocket.

The approximate 2.4 GHz WiFi signal range is shown here for various antennal gains. https://www.tomsguide.com/us/2,review-125.html The range is also dependent on the data rate. A 9600 bps data rate signal will have a long range than a 115 kbps data rate signal.

Instead of posting radio questions, try googling your questions. There are hundreds of ham websites that discuss all of this in detail.

Bob
 
:wink:Ummmmm, why Google when Bob does an excellent job distilling technicalities for the common person?:wink: Read Bob, then Google with understanding and force! :grin: Kurt
 
googling doesn't always yield good information that the average person could understand. I have tried googling antenna questions and couldn't really find anything relevant. That's why we have forums.
 
This is one of the few ham technician study topics that is actually helpful to our rocketry application. The rest of the ham license - not so much.
 
To give a quick (and simplified) idea as to the matter of why frequency maters it is like this:

First, there is a relationship between frequency and wavelength. One wavelength is the distance the electricity traveled in a given cycle. Double the frequency, you halve the wavelength. Now, ideally an antenna half, which is what we are dealing with, is a multiple of 1/4 the wavelength.

Now going with the overly simplified model, a 2400 MHz antenna (for wifi) will only be 3/8 the length needed for 900 MHz. This will cause most of the energy to be reflected back into the transmitter and in short lead to horrible range. This has all been way simplified, and one should consider that most "duckie" antennas are not as simple as a wire the length of the antenna. And the characteristics of how they put the wire in there and what white they use affects how broad a range it works, etc.

For my Egg Finder, I used the supplied solid antenna. I turned the receiver 90 degrees from the instructions and moved it to the far end. This left my receiver antenna completely inside the case. I saw Chris saying that 500 feet on the ground is good. I tested my range by placing the transmitter in place for my rocket and laying it in the front yard. Then I walked a path that put my behind the houses across the street and got to about 900 feet losing between 20 and 40 percent of the packets. I then went a different direction up a slight rise with no significant items in the path. That way, I was about 2500 feet when I experienced the same loss, quickly losing the rest as I dropped below the high point.

My L1 flight took my rocket out about 2200 feet and I had good reception all the way back.
 
New antennas... You can get up to 11,000 with the stock antennas and up to 18,000 with the rubber duckie antennas. I'm guessing your using the wrong antennas.

You can get MUCH further with the stock antenna on the Tx and a cheap ebay antenna on the Rx. I'll post more in a couple of days when I get all my data and photos downloaded, but I tracked a flight to 22,621' up, and ~16km/9nm downrange last weekend. edit: In the excitement of that flight, I forgot to add that I tracked my L3 flight to 16,292' with a similarly equipped EF last weekend, too.
 
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You can get MUCH further with the stock antenna on the Tx and a cheap ebay antenna on the Rx. I'll post more in a couple of days when I get all my data and photos downloaded, but I tracked a flight to 22,621' up, and ~16km/9nm downrange last weekend. edit: In the excitement of that flight, I forgot to add that I tracked my L3 flight to 16,292' with a similarly equipped EF last weekend, too.


Oh certainly. I was referring to wire antennas on both RX and TX. As for rubber duckies the highest that has been recorded on the thread is 18,000 with connection the whole time. If you've gone higher definitely go and post your data to the eggfinder thread!
 
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