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Hi All,

I would just like to collect some info on your video receiving aerials that you use. The info may help beginners choose the correct aerial or may even give the rest of us something to think about, who knows !

I would like to split the question into 'short range' up to 1/4 mile, 'medium range' up to 1 mile and 'long range' up to 5 miles. If anyone dose over that we can call it 'extreme range'.

It will also be handy to know you TX power for the system...

So to start things off :

For TX power of 10mW

Short range I use a 1/2 wave disc patch pointed at the plane by a helper

Medium range I use a 22 turn helical pointed at the plane by a helper

For TX power of 200mW

Short range I use a 1/2 wave disc patch pointed at the plane by a helper

Medium range I use a 1/2 wave disc patch on a stand

I have not done much over a mile so far due to my R/C system range.

Thanks Terry UK

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I'm surprised that no one has added their comments to this thread.

I don't have anything new to add. However, I will say that the standard whip that is ships with the video receiver is the worst possible choice. An omni is not good for our application.

For overall decent performance, a patch antenna with 5-8dBi of gain is a fine Rx antenna choice for nearly everyone. The beamwidth is sufficiently wide to reduce the need for precise aiming, but small enough to help reduce multipathing. And building your own is easy and cheap (Goof Proof Patch costs under $10.)

Although I am an active promoter of using improved antennas to extend range, I do feel there is a point where increasing Tx's RF power is a more practical solution. Just keep in mind that every 4X RF power increase will double the range. So, beyond a patch or simple Yagi on the Rx, and a Ground Plane or Turnstile design on the Tx, if more range is needed then it is worth looking into the Tx's RF power. We are already dealing with ham equipment, so licensed users can legally increase the power as they see fit.

As a final comment, the video Rx's performance is key to extending range too (probably more important than Tx power). In absence of any real pusblished data, the best course of action is to buy something that has a good track record.

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Yes I too was surprised that nobody wanted to share thier info. I started this thread a long time back in hope that it would provide info for beginners and may be open up some new ideas for the rest of us that may be stuck in our ways !

Things have changed for me since then and I now use my auto tracking patch for most jobs as its easy to use.

I still use 10mW for up to 1/4 mile and 200mw for anything more, I guess that it should give me 2 miles but I have never used it past 1 mile due to the R/C starting to glitch.

Terry

Edited by Terry

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Had missed this one... blush.gif

Okay, let's go:

Short range:

As cheap, small, lightweight and easy system: 9V batt-powered integrated 10mW TX and CMOS cam, with the standard whip antenna on the receiver. Pretty reliable. I have the same one with an internal Li-ion battery. Turns out to be lighter.

Same TX but with a CCD cam, 12V powered (much heavier but much better quality also)

All these often fly on parkflyers, and have the advantage of being legal regarding TX power. The CCD one also has some rights to fly on bigger ones though :rolleyes:

Medium range:

100mW TX, 3dBi whip, 620 lines CCD and 8dB panel on the ground.

From this summer on we'll try to achieve long (or extreme? :rolleyes: ) range with a 30dBi pre-amplified panel that should arrive at my place by tomorrow :D , keeping the 100mW TX. Really looking forward to test that.

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I fly all my own stuff of course ;)

My workhorse is the 200mw 5v tx which I velcro on whichever plane I'm flying. The standard whip usually does the trick but I'll use the low profile disk on belly landers.

I fly almost exclusively low/medium range and I use the same ground setup for each, depending on my mood... if I'm traveling light, I use a basic reciever with 8dbi patch. When I need the big guns I'll pull out a pair of 14dbi patches and the new diversity receiver.

Regards,

Bill

Edited by yb2normal

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new diversity receiver

Where's this one?? :blink:

Seems that there will be a candidate for next order :P

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Operators are standing by ;)

I am getting ready to move it into limited release, I have to get labels printed and write the documentation. I also want to generate some good test footage to show it off.

I just received a version with a built in video overlay that will show a '1' or '2' on the screen depending on which receiver is in use. Since you can't tell the video is switching just by looking at it, I needed a way to prove that it really was switching!

Regards,

Bill

Edited by yb2normal

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OK, I'll wait then, I'll surely have to place an order within next month :P

It's interesting as I know someone who has problems with multipath interference indoors. Do you think it would get better? I've heard that it should, and he found a 4-way diversity switch. But the price was prohibitive :wacko:

As he uses his system professionnally he really needs something that works...

Edit: How stupid I am, just realised the link with the other thread.

Edited by Kilrah

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Just found this thread....sorry for coming to class late!

As a newbie, I can't offer much, except to other newbies, many of whom are not in the

"build-it-yourself" mode. There have been many posts from newbies asking about the best antenna combinations, and "....where can I buy one?"

I just started building stuff, and I can say that there is nothing more satisfying than building something yourself.....that actually works! Mr. RC Cam helped me along the way, I might add.

I am running a Part 15, 1mW (probably less) Tx with a 1/4 wave Ground Plane "spider" antenna. My Rx uses a 13db patch that I bought here http://www.fab-corp.com/

These patch antennas are selling for twice the money on the many "surveillance" web sites. These guys have lots of neat stuff at great prices, and ship the same day you order!

The above mentioned antenna combination gets me a reliable 750' LOS (remember, 1mW Tx!)

Yes, I know the modified Tx antenna will violate the Part 15 rules, but I have an "Experimental" license from the FCC which allows me to "dabble" up to 10mW.

This is a short term license. Anyone can get one. There might have been a fee, I forget.

Where can I buy a 10mW Tx(2.44) in the US? All of the sources that I have found are in Europe.

Tom

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Guest Lemming

I'm not sure what frequency at which you are all operating, but I will be triggering the IR remote on my kite aerial rig with a 433.9 MHz 2-channel relay control. I am somewhat torn on what antenna to use, because I am

A ) unsure what the output (RF) impedance is on the transmitter. I assume/hope that it is 50 ohm so I can at least attach a 1/4-wave antenna to the "car alarm" style transmitter that comes with it. Because of the pattern of a 1/4-wave (Isotropic, as in dB"i"), to get better reception with this type of "no gain" antenna, one must turn it sideways/horizontal to get a better reception to high in the sky versus keeping it vertical and getting linear/horizontal reception better.

B ) unsure what the input impedance is on the receiver. Again, I hope that it is 50-ohm tuned for the same reasons that I hope the transmit side is 50-ohm

Now, I'd love to use a patch, because I know the gain pattern of them, and they are great...or even a Yagi or LPDA tuned for that frequency. But I am unsure if the 70cm HAM band (in which 433.9 MHz falls) is such that there will be antennas with gain readily availible. I readily admit that while I come from a 14-year RF electronics background, designing antennas is not my forte'...it's a whole other beast. I have access to all the equipment I'd need to make them if I only knew enough how to do that...sad huh?

I do know this much; putting 1/2 wave and 3/4 wave and other such odd fraction-of-the-full-wave antennas on systems not properly impedance-matched for that type of antenna will not yield good results. Many patches (and correct me if I am wrong) are already designed to give a 50-ohm match by default, since "most" of the RF world uses 50-ohm impedance outputs.

All that being said, please add to this post, correct it where necessary, and otherwise make suggestions as to what type of antenna might be availible for the 70cm HAM band.

I know I could always just sift through the huge product list that TESSCO carries (specialize in antennas and such), but I lack the time to do that.

I wanted to mention that for a tiny little cost, you can get monolith RF amplifiers for your transmitters that are little bigger in size than most small house spiders, and their operating range is from 100MHz up to 3GHz with a typical gain of about 18-22dB depending on the frequency you will be giving it. Now, for those of you who don't know, every 3dB increase represents a doubling of the wattage. So, in other words, an 18dB increase (gain) in your transmit power is 64 times more powerful in wattage than the signal you start with. So, an quick, easy, and cheap way to improve your range severely would be to buy one of these (or several - they're cheap!) monolith amplifiers. I will get the product and source info for anyone who is interested. You will need to be able to cut the RF trace on your transmitter's output line and insert the amplifier into the circuit, and there is always the chance that your VSWR (Voltage Standing Wave Ratio) will change because of the change to the circuit, but even as a "meatball surgery" remedy to your range issues, these amplifiers are very robust and can handle not being optimized in the circuit. And then a little heat-sink never hurt anyone

Edited by Lemming

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I use a 1.2 system with a 400mw TX with a GP Patch, and the standard whip antenna on the TX. I have flown about a mile away(maybe a bit more) with no decrease in video quality, and haven't tried to fly farther for fear of glitching and augering in the airplane. Is there any way to increase the range of a standard airplane controller? I wish I could safely fly at least five miles, instead of just one mile! Anybody done this?

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Today we tested a 3w Tx. We did the range test on the ground having the TX on a 100 m. high hill and the Rx 9 km (5.6 mille) far way but having direct LOS.

The Tx was using a omni 5 db gain rubber antena while the Rx was tested with the omni stock one (some snow on the image) and with the same omni 5db rubber antena used on the TX (clear image). We also tested a 9 dbi RX antena but looks like the kind of RG58 coaxial wire we used was not the best one and the aerial did not work at halve the distance even having the aerial on a 9 feet tripod.

In flight test will be delayed a little more.

Does any one have references from these guys and her products? http://www.ead-ltd.com/

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Hi - I'm John from Bakersfield, CA. We have beautiful flying weather here right now. I don't record video because right now I'm interested in simulated piloting. I use a 600mw BWAV system on a wingo. Monitor is a 7" Xenarc Hi-Res LCD, enclosed for outside viewing, and magnified with a page size Fresnel lense. This turned out to be a very good real time monitor solution. I get the best reception with a commercial 8db patch for receiving, sitting on or near the ground pointed straight up, (as suggested by Yb2normal). The transmitting antenna (Rubber duckie) is pointed straight down, all the way underneath the airplane, so that on landing the antenna hits the grass and bends 90 degrees back. This is not a very aerodynamic installation, but I am happy to report that this configuration results in drop-out free reception for at least a 200 yard radius, with only minor flickering in some orientations, which is somewhat annoying but not at all panicky. The only dropouts I have noticed occur straight overhead, but here it is relatively easy to locate your plane. I have been able to trust the system so far as to fly the road surrounding the park and watch the cars drive underneath at an altitude of about 35-40'. I'm also able to fly above an open field at about 10 feet altitude and look at all the animal tracks and holes. With this configuration, it is also easy to land on camera only. (Anyone who knows the flight characteristics of a properly balanced Wingo in No-Wind conditions will understand this better). Basically I'm having a lot of fun skimming the treetops at the local park on live video (Simulated piloting).

One trick I want to report, is with the foamy wingo, when it blows more than about 8 Mph, it gets tippy, and unstable. I am embedding a drinking straw into each wingtip at the CG line, and putting in fairly tiny fishing weights into the wingtips, more weights for more windy conditions. I will report flight characteristics in different wind conditions, when more data is gathered. Thanks all for now, happy Flying. -John

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