Thanks Trnquill,
Thanks Alex,

Now, I get more information about some kinds of atennas.
I am going to build this one for mine own.

However, I still have a question here about RX Airwave 5.8.
Maybe my Eng is not good and this is hard to explain.
I am attaching here the picture which describe more detail about what I saw on my RX.
Please have a look at this and tell me it the RX is wrong or it is normal.
http://www.flickr.com/photos/duypham11/6008412805/

...

Anyone forsee any issues with soldering a skew planar or clover leaf to a flange type SMA connector?

Originally Posted by Mictronics

And for what purpose is that kind of "measurement" methode?

Just for testing if 2 poles are short circuit or not. The TX is not, but the RX.
Is this normal or not?

Thanks,
Duy

i wanna make a Skew-Planar and a clover leaf
could somebody tell me the Right Handed and Left handed think that i dont understand well?

Does it mean that the antennas sould not be the same , so one have to be RH and the other LH?
thanks guys

...

Originally Posted by patricklupo

Anyone forsee any issues with soldering a skew planar or clover leaf to a flange type SMA connector?

That looks like a great fit for a skew wheel! I'm going to order a few of those connectors and see if they are easier than my BluBeams.

Thanks,

-Alex

just finish my antennas for 1.2 and looks like this...
i tested them and they are super..

Originally Posted by Mictronics

Both antennas must have the same polarization. So either both LH or both RH.

For skew-planar and cloverleaf, when you look from the side on the antenna, and the element you look on leans to the right, then it's RH polarization.
Leaning to the left is therefore LH polarization.

For comparison, this is RH:
http://www.rcgroups.com/forums/attac...mentid=3978043

Welcome to the world of circular polarization. You can now put your old antennas in a box and tuck it away.... forever

-Alex

a couple pics of my CL and SPW 1280mHz antenna set I just finished.

easy build, PITA to solder up lol, Thanks IBCrazy I can't wait to test them.

I have one question tho, will switching to circular polarization help eliminate interference on my 2.4G rc tx/rx since they are linear? and could you add a 2.4G CL and SPW to you rc tx/rx in the other polarity or would that hinder your radio link?

Thanks
Jon

Originally Posted by jhtitan

a couple pics of my CL and SPW 1280mHz antenna set I just finished.

easy build, PITA to solder up lol, Thanks IBCrazy I can't wait to test them.

I have one question tho, will switching to circular polarization help eliminate interference on my 2.4G rc tx/rx since they are linear? and could you add a 2.4G CL and SPW to you rc tx/rx in the other polarity or would that hinder your radio link?

Thanks
Jon

Unfortunately, no. Frequency and polarization are two completely different things.

Also if you check my youtube page you'll see that I bend little hooks on the ends of the wire the exact same length as the feedpoint gap. this makes it much easier to solder and makes it much stronger as well.

-Alex

Thanks Alex. I got a chance to briefly test out my SPW and CL antennas today and it was clear signal all the way with no drop-outs. Previously I'd always get dropouts and lots of static using omni antennas when flying the same route.

WOW patrick those look great. What kind of wire did you use? Looks pretty thick.

I know you mostly fly low altitude with your quad, but watch out if you ever decide to punch the throttle and get some altitude - looks like the body of the quad could block your signal some. But with 1.3ghz you probably won't even notice it unless you venture further out. Just noticed that and thought I should give a warning

- Jeff

Hi Jeff, thanks. I used 1.6mm brass wire sold at OSH hardware as 25ft spools in the welding/tools section and flange SMA connectors.

Yep, the CF base will block signal if the copter's directly overhead but not when out a ways. I flew out half mile with omni antennas on video Tx & Rx last weekend to test my FRSky. R/C link RSSI stayed pretty much 100% the whole way but video started to get fuzzy toward the end. Gonna retest with the CP antennas when I get the chance. I'm not looking for range past 1/2 mile but better reception quality and it looks like CP delivers.

Originally Posted by IBCrazy

Unfortunately, no. Frequency and polarization are two completely different things.

Also if you check my youtube page you'll see that I bend little hooks on the ends of the wire the exact same length as the feedpoint gap. this makes it much easier to solder and makes it much stronger as well.

-Alex

thanks for the tip. not sure what my issue was the last 2 attempts at flying FPV. I am using 2.4G FrSky tx/rx system and range testing on the ground was fine. On the first day, my 5th flight with all my FPV gear mounted was going great when I lost radio link completely. fixed up the plane and swapped cameras (lost my good camera in the crash) Took it back out and again everything was going fine and then boom, no radio link. I didn't lose video link til about 5-10' from impact both times. plane was pointed away from me and a bit behind me. both crashes where in about the same area of my flying field, but its an area I have flown in a lot under normal conditions (no FPV) with no problems at all. and the link was lost at about 100' away from me after flying much further than that in other directions. My video system is the Range Video 1.3G 300mW TX and RX with 5dB whips until now.

Jon

oh and I have added the 60cm antennas to my FrSky rx and have them routed to the tail about 6" apart from each other, with about 22" between them and the vid tx.

Jon

Hello, which measurement is correct?
From the corner to the center(green) or to the soldering place(yellow)?
Also I have to measure to the corner of bending(blue) or to the center of wire(red)? Thanks

So are you suggesting that you add the length of the feedpoint gap to make the hook or that the hook is equal to the feedpoint gap and subtracted from the quarter wavelength wire arm?

I want to build a pair of antenna for 5.8GHz and I am guessing that build accuracy gets more critical at these wavelengths?

Peter

Originally Posted by IBCrazy

Unfortunately, no. Frequency and polarization are two completely different things.

Also if you check my youtube page you'll see that I bend little hooks on the ends of the wire the exact same length as the feedpoint gap. this makes it much easier to solder and makes it much stronger as well.

-Alex

Alex
Grips is flying his Quad in Canada. Wants 500-700 feet of clear video. I recommended a Range Video on 5.8GHz 200mW system with an IB Crazy SP and CL setup. Your thoughts would be appreciated.
Thanks,
Neal

Hi I recently changed to 5.8ghz from 1.2ghz, I am using the airwaves rc and immersionrc Tx. I found that when powering the Tx using 12v 3 cell lipo I was getting herringbone lines on my monitor but reducing the voltage to 6v solved the issue (6v Ubec). I tested the system but range was rubbish using the omni antennas. I made a set of cp antennas but still getting dropouts at 200m! My question is has the power has been reduced in the Tx by reducing the input voltage? And has anyone else had the same switching interference issues with 12v?

Originally Posted by Nobert

Alex
Grips is flying his Quad in Canada. Wants 500-700 feet of clear video. I recommended a Range Video on 5.8GHz 200mW system with an IB Crazy SP and CL setup. Your thoughts would be appreciated.
Thanks,
Neal

That will do 1000+ feet with ease.

-Alex

Originally Posted by Peter Seddon

So are you suggesting that you add the length of the feedpoint gap to make the hook or that the hook is equal to the feedpoint gap and subtracted from the quarter wavelength wire arm?

I want to build a pair of antenna for 5.8GHz and I am guessing that build accuracy gets more critical at these wavelengths?

Peter

Yes, that is correct.

Hi!

I just ordered the 5.8 GHz Bluebeam Cloverleaf/Skew-Planar Wheel Antenna Set (RHCP) from readymaderc.com. I plan to use the set on my FoxTech Rx/Tx. What confuses me is that readymaderc.com writes on their site:

Foxtech will require an RP-SMA female to SMA female adapter.

while videoaerialsystems.com says for the same set on their site:

Foxtech will require an RP-SMA male to SMA female adapter

Which adapter is now the right one, or are the sets from both vendors different?

All the SMA, RP-SMA terminology is somehow confusing, but let me sumarize my findings as follows:
male always has the thread inside, resp. on the female thread is outside.
SMA male has a pin, SMA female has a hole.
RP-SMA male has a hole, RP-SMA female has a pin (RP = Reversed Polarity)

Now, both my Foxtech Rx and Tx have a pin and the thread outside, i.e. RP-SMA female, so I guess videoaerialsystems.com is correct with proposing a RP-SMA male to SMA female adapter.
Any comments from the gurus?

Thanks a lot in advance & regards from sunny austria,
Christian

There is nothing more confusing than RF connectors... Nothing. You need SMA female (to join with the antenna) to RP-SMA male (to join with the RX/TX). Basically you need to convert from RP-SMA male to SMA male. So the adapter is SMA female to RM-SMA male. Looks like I need to fix the website.

_Alex

Hello Alex, I received your two antennas and I'm really happy with them.
Now I need to understand how to best position them.

I am flying a quadcopter and at the moment the TX with the Cloverleaf is on the top pointing upwards.

The receiver with the SPW is positioned beside me with antenna pointing up.

Is this the best position?
Should it be better to position the TX under the quad pointing downwards?

Thanks for any reply.
Cheers,
Emile

That works fine. I would put the TX antenna below the quadcopter aiming down to clear the Fresnel zone, but that's all.

Hello IBCRAZY,
I was wondering, since in your tutorial for building this and the cloverleaf, the sizes of the elements are calculated using 0.035" wire, which is 0,85 mm, if I wanted to build it with 2mm wire, I guess the elements should be shorter, my question is , by how much? Is 1-1.3% shorter a safe guesstimate?

We are talking more than double the copper...

Also bought the 5.8bluebeam antenna today ( finally in stock) cant wait to test these works of art. Hoping to increase my range from 200m!

Originally Posted by starjet

Also bought the 5.8bluebeam antenna today ( finally in stock) cant wait to test these works of art. Hoping to increase my range from 200m!

You got lucky I guess. Just went to buy one, but my cart said that they were out of stock....

I set up e-mail notification, so they must have went fast! IBCrazy should set up in China and mass produce these (make a fortune). Now I need to sort out the "herringbone lines" issue on my 600mw Tx.

All of my products are hand made here in the USA. I will not farm this stuff out to China. I actually hired a manufacturing engineer who is designing a CNC machine to make these faster. We are changing some of the manufacturing techniques as well.

I have a few BluBeams left in stock. I will have to clear the system of orders that didn't get processed correctly to get the correct quantity on the site.

-Alex

Originally Posted by MarcAntonio

Hello IBCRAZY,
I was wondering, since in your tutorial for building this and the cloverleaf, the sizes of the elements are calculated using 0.035" wire, which is 0,85 mm, if I wanted to build it with 2mm wire, I guess the elements should be shorter, my question is , by how much? Is 1-1.3% shorter a safe guesstimate?

We are talking more than double the copper...

Sort of...

Wire thickness counts. 1.3GHz was calculated for .0135" wire but when you get to 5.8GHz .023" wire works best. For 2.4GHz I use .030". I need to know your frequency to determine how much shorter you need to make your wires. A blind guess tells me 1% is about correct, though.

-Alex

Originally Posted by IBCrazy

All of my products are hand made here in the USA. I will not farm this stuff out to China. I actually hired a manufacturing engineer who is designing a CNC machine to make these faster. We are changing some of the manufacturing techniques as well.

I have a few BluBeams left in stock. I will have to clear the system of orders that didn't get processed correctly to get the correct quantity on the site.

-Alex

Just kidding bout China, nice to see ur keeping it in the USA!

Originally Posted by IBCrazy

Sort of...

Wire thickness counts. 1.3GHz was calculated for .0135" wire but when you get to 5.8GHz .023" wire works best. For 2.4GHz I use .030". I need to know your frequency to determine how much shorter you need to make your wires. A blind guess tells me 1% is about correct, though.

-Alex

It's 1040mhz...... wire is .075" ... it's about 2mm.

Originally Posted by IBCrazy

Sort of...

Wire thickness counts. 1.3GHz was calculated for .0135" wire but when you get to 5.8GHz .023" wire works best. For 2.4GHz I use .030". I need to know your frequency to determine how much shorter you need to make your wires. A blind guess tells me 1% is about correct, though.

-Alex

Hi there,

I really have a problem with such type of antennas. I'm ready around all internet antenna sites, and no one is talking about this.

The orginal cloverleaf design is quite a bit different and based on a semi plane four assembly. It's radius is very different than this one described, and no way to find any 105° angle ruling.

So why i'm sceptic and admirative too if this really works better for anyone.

Is there any case study about this or some book talking about it somewhere ?

BTW, i'm experiencing a strange problem with my 5.8 Ghz TX and RX. My TX uses an omnidirectionnal antenna 3db.

My reception is made by a 19db patch antenna, and i puted it like usual with horizontal polarization. I'm using an antenna tracker from Myflydream which is offering an accurate pointing.

Sometimes, the tracker loss it's data due to transmission problems. It uses audio channel, and the tracker stops turning. Reverting to an acquiring state, it runs fast to the tracking point. The angle correction is close to around 20° at most. The antenna is supposed to reach a 30° angle, and it's weak between 6 and 8° on both sides from center. So why it's loosing signal and have to run for correcting the new tracking angle.

Anyone here experienced such bizarre behaviour ?

Let me know about your research. I'm newbie but very interested by the cloverleaf concept.

Regards.

A 30 degree angle means that the antenna gain is 14 db, not 19. 19dbi is more like 15 degrees (ie 7 degrees off center).

Build or buy a cloverleaf and skew wheel antenna set. You will put your linear system in a box and never look at it again.

So why haven't you found this looking at other internet sites? Would it surprise you if I told you someone was wrong on the internet? I have found many tutorials that are just plain wrong. I have found many "wonder antennas" that are just garbage. Read around the FPV forums. Ask anyone how they like their CP antennas. The results speak for themselves

-Alex

Alex If I build my 5.8ghz antenna using 4 pieces of wire not 2 would I have to change the overall length of the wire?

So I have each wire is 54mm with 13mm at each bend. The feed line is about 3mm Will I need to shorten the wire for each arm?

Originally Posted by IBCrazy

A 30 degree angle means that the antenna gain is 14 db, not 19. 19dbi is more like 15 degrees (ie 7 degrees off center).

Build or buy a cloverleaf and skew wheel antenna set. You will put your linear system in a box and never look at it again.

So why haven't you found this looking at other internet sites? Would it surprise you if I told you someone was wrong on the internet? I have found many tutorials that are just plain wrong. I have found many "wonder antennas" that are just garbage. Read around the FPV forums. Ask anyone how they like their CP antennas. The results speak for themselves

-Alex

I'm wondering if you can explain the simply off principals for this antenna and why it has so good results.

If this can be dangerous for you heath due to gm and cm radiations and not enough knowledge to play with ?

Some graphs for distance to power and safety use.

Brief compare with other antenna type.

You know, as a consummer, i'm always comparing. This is not because someone says it's wonderfull that i would agree with closed eyes (without any doubts).
As you are saying it, internet is full of urban legends like using 900mhz band for video transmission is good for FPV.
BTW, i've been searching for relevant information about the cloverleaf antenna, and this is what i found so far : http://www.patentgenius.com/patent/6518931.html

Can you review your experience and give us the HC compliancy test results so far ? I mean, what about bouncing, rays, max power, power to distance ratio, efficiency, etc...

As your idea seems to be an improvement, i'd like to have some more explanation if you don't mind.

Regards.

Originally Posted by lothar2048

.....
As your idea seems to be an improvement, i'd like to have some more explanation if you don't mind.

Regards.

Actually there is more then enough technical information on CP antennas to answer all your questions in these two threads:

http://www.rcgroups.com/forums/showthread.php?t=1389925

http://www.rcgroups.com/forums/showthread.php?t=1147430

For example, here is my response from the second thread above which addresses your question on the radiation level:

http://www.rcgroups.com/forums/showp...&postcount=341

OMM

Originally Posted by IBCrazy

All of my products are hand made here in the USA. I will not farm this stuff out to China. I actually hired a manufacturing engineer who is designing a CNC machine to make these faster. We are changing some of the manufacturing techniques as well.

I have a few BluBeams left in stock. I will have to clear the system of orders that didn't get processed correctly to get the correct quantity on the site.

-Alex

Alex,

When will you have more 5.8Ghz BluBeam antenna sets in stock?

I have question for Alex and Old Man Mike regarding the geometry of the Skew Planer wheel and the Clover Leaf CP Antenna.

Firstly i must thank you guys for sharing this information with us. It has made my FPV experience much more enjoyable and for me i love to be abel to make these things myself.
Thanks for making that possible.

My questions are as follows.

In the very first post on this thread there is a video showing the Geometry of the SPW and the over lapping angle of the lobes as 17.1 degrees
How important is this angle?
Do you know what the overlap angle is for the Clover Leaf antenna?
I find the angle of the lobe of teh SPW needs to be different from the Clover leaf to achieve the 17.1 Degrees Overlap?
Is this correct?


Also I want to check that the length of the arc of each lobe should be 1/2 a wave length correct?

Is the angle between the straight parts of each lobe Critical?

Is the shape of the lobe for the Clover leaf the same shape as it is for the Skew Planar wheel,
for the same frequency?
I am assuming it is but am not sure.

From my 3D models the lobes for each antenna are different shape

The reason i am asking is that i would like to make a Jig and a Template to make fabrication of these antenna much easier and quicker.
And possibley offer the Jigs to others

I have found my 900mhz antenna to require repair quite frequently...but thats probably due to me landing on it fairly often!
And its mounted on top of my tricopter!

Please see a very rough example of my jig for making / repairing my Clover leaf.

Please also see attachments of sketchs for the lobes and over laps of the Clover leaf and SPW antenna withe the angles and overlaps easier to see.

Thanks in Advance

Ben

Your geometry looks correct to me. However, let me say that you are way overthinking this. I overlap by about 15 or so degrees on the skew-wheel. OMM does not overlap at all. Both antennas work great. Thus it's not critical! Just keep the lobe length correct and you will have it.

-Alex

Great!!

Thanks Alex i appreciate your feedback

Im glad you said that as i was really begining to scratch my Head!

Cheers

Ben

Subscribed

My first attempt at a SPW, made a cardboard jig and it worked pretty good. Took alot longer than the CL, but I didn't need a jig for the CL.

Just finished my first 5.8 GHz SPW, only the second antenna I've built. Whew, that got a bit tricky, with improvisation and no jig used on this one and I'm not too happy with the look of the result. It's ugly and imprecise at the very top, at the end of the coax center conductor, and one of the horizontal arms is a little higher than the rest (I ended up cutting to fit the coax in the middle) but I figure it should at least help in figuring out if it needs to be prettier to boot.

Earlier I made one of Hugeone's "turbine" antennas as my first case of self-built antennas, and it definitely turned out better-looking, but we'll see how it/they work! I need perfection since we are only allowed 25 mW at 5.8 GHz and 10 mW at 2.4 GHz for dumb video links in Europe. I used 0.7 mm (copper) wire, I think; at this size it holds itself together at least. There are some mechanically weak points on this one now, but I'll try to safeguard it against too many bumps.

Originally Posted by volto

My first attempt at a SPW, made a cardboard jig and it worked pretty good. Took alot longer than the CL, but I didn't need a jig for the CL.

That looks good Jerrod! Nice smooth bends. When do you intend to fly it?

-Alex

Originally Posted by Helldesk

Just finished my first 5.8 GHz SPW, only the second antenna I've built. Whew, that got a bit tricky, with improvisation and no jig used on this one and I'm not too happy with the look of the result. It's ugly and imprecise at the very top, at the end of the coax center conductor, and one of the horizontal arms is a little higher than the rest (I ended up cutting to fit the coax in the middle) but I figure it should at least help in figuring out if it needs to be prettier to boot.

Earlier I made one of Hugeone's "turbine" antennas as my first case of self-built antennas, and it definitely turned out better-looking, but we'll see how it/they work! I need perfection since we are only allowed 25 mW at 5.8 GHz and 10 mW at 2.4 GHz for dumb video links in Europe. I used 0.7 mm (copper) wire, I think; at this size it holds itself together at least. There are some mechanically weak points on this one now, but I'll try to safeguard it against too many bumps.

Nice build! I think it would have been much easier to use a copper jacketd steel wire, though

-Alex

Originally Posted by IBCrazy

That looks good Jerrod! Nice smooth bends. When do you intend to fly it?

-Alex

Thanks! Not sure when I will get a chance to fly it, but I will be using it on the ground, with a CL (the one you built) on the plane. I was hoping to get my Daemon style mechanical headtracker working before the FPV maiden of my 2 meter Phoenix 2000 that the CL is on. Also want to get my Remzibi OSD on it... so I don't know when all that will be. Hopefully soon, this thing is gonna be fun!

Jerrod

Originally Posted by Helldesk

I'm not too happy with the look of the result.

Belive me, with 5.8Ghz, a nice look is not at all related to a good working antenna. Without propper means to measure it's performance it's shooting in the dark anyways. Luckily those antennas are fairly wideband and as such you will see an increase in video quality that is a quantum leap compared to linear antennas. For optimum results though you would have to be able to make it resonant on the frequency your tx and rx operate on. Without a propper way to measure the return loss this is impossible, especially on such high frequencies as 5.8Ghz.

Markus

Originally Posted by IBCrazy

Nice build! I think it would have been much easier to use a copper jacketd steel wire, though

Thanks! I used what I could find - another option would have been (uncoated?) steel piano wire, either 0.4 or 0.8 mm. Is the wire thickness for 5.8 GHz significant?

Hi Guys

I have also been making some 5.8Ghz antenna for my FPV quad.

I decided to make a Jig and Template for mine.

I used 1mm solid copper wire from some heavy duty earth cables we had lying around on my construction site.

Here is the prototype system

Let me know what you think

If anyone is interested to buy these Jigs and Templates please let me know if the demand is high enough then I'll see about getting some made.
I have drawings for 900Mhz 1280Mhz 2.4Ghz and 5.8Ghz

Cheers

Ben

Originally Posted by wazzer

Hi Guys

I have also been making some 5.8Ghz antenna for my FPV quad.

I decided to make a Jig and Template for mine.Ben

Nicely done, Ben. Have you made any SWR measurements on the completed antennas?

OMM

Originally Posted by Old Man Mike

Nicely done, Ben. Have you made any SWR measurements on the completed antennas?

OMM

I thought I'd post two pictures of the measurements of one of the skew planar wheels I made. The sample shown is made for 5.645Ghz which equals to channel four in the so called "band E" that is used with Foxtech et all types of setups. The first picture showes a smith chart along with the return loss, the second the SWR with the same return loss. The two graphs show two different sweeps also showing that the values wobble a bit up and down by two to three dB.

I'm pretty happy with the results and after countless hours of trial and error and work, I now finally found a way to fine tune those 5.8Ghz antennas to any spot on frequency of choice. I don't know how it is for others, but to get to that point turned out to be VERY difficult in this frequency range.

Markus

This week I made 7 windmills and 5 fans at 5800mhz, they all shown a return loss of -20db or better. I make the center conductor on the long side, if freq. id too low, I add a bit of solder beefing it up. Quick and easy

-Hugo

Originally Posted by Old Man Mike

Nicely done, Ben. Have you made any SWR measurements on the completed antennas?

OMM

Hi Mike

No i havent, i dont have access to that type of equipment and wouldnt know where to start.

I tested the set of antenna in the pictures out yesterday and to be honest i wasnt all that impressed i had a some fuzzy images through the goggles at times flying in a wide open park. I guess i was expecting a prefeect image at all times. I was flying FPV within LOS and i was nt flying around any obsticles.

I would love to send you a set to test if you would be so kind?

These were built to 5.8Ghz measurements supplied by Alex at the begining of this thread.

They were not built to a specific channel within the 5.8 "Band" as i thought these were wide band and not so sensitive?

Was I wrong to assume this?

I am using the Foxtech 200mw Tx and Rx but i forget the channel i am using at the moment.

I am also using a "few" RF adaptors to attach the antenna to the TX and Rx do these have an effect on the performance?

On the Tx i use a RP adaptor and then a Male to female adaptor and then the RG316 Coax attached to the antenna. (I only had a male pigtail avaialable)

On the RX I use the RP adaptor then a 90 degree elbow then the RG316 pigtail attached to the antenna.

I will post some more pics this eveing when i get home from work

I appreciate the feedback


Cheers

Ben

Originally Posted by Hugeone

This week I made 7 windmills and 5 fans at 5800mhz, they all shown a return loss of -20db or better. I make the center conductor on the long side, if freq. id too low, I add a bit of solder beefing it up. Quick and easy

-Hugo

Hmmm, -20dB or better.... ok.... You have looked at my charts did you?

Markus

Originally Posted by wazzer

These were built to 5.8Ghz measurements supplied by Alex at the begining of this thread.

They were not built to a specific channel within the 5.8 "Band" as i thought these were wide band and not so sensitive?

I probably differ with my opinion from the other experts here and I figure this is because I mostly centerd on 5.8Ghz right from start. There are IMHO a few things which are fundamentally different to the other aparently more common frequencies.

First off, the FoxTech tx/rx which is really a good system to start with is having a specialty. If you look at the channels and frequencies it uses you see that they use 5645 up to 5705 and then there is a big GAP to 5885 up to 5945 Mhz. As a result, an antenna built to the center frequency of 5800Mhz is really suboptimal as its far away form any useable channel. Note, this holds true only for the "Band E" variants of this rx/tx, but this one is really the most popular one sold in virtually any asian store.

The other problem is that the higher the frequency gets, the lower the tolerances. I invested a lot of effort to buy and or build precise instruments to build my antennas as precisely to measure and with as reproduceable results as possible. Still, not a single antenna is totally the same as the previous one. That's just because the variance in precission I'm able to achive still differs enough to make up for the different result. Ok, it of course depends on what set of quality requierements we apply. But I'm from Switzerland, you know the guys with the precise watches and so on. :-)

I had the ocasion to test antennas that I originally made back when I built antennas just to measure like you did but also antennas made by several others also including antennas from well known sources I don't want to name here. Well, they are usually dramatically off. They resonate up to 200Mhz away from where they should be. CP antennas are luckily wideband to a degree, but an antenna having a return loss of say < 20dB at the frequency I intend to use it is really not something suitable for best results.

So, my bottom line remains the same. You need a way to measure your antenna. You also need a way to tune the antenna to make it resonant at the frequency you intend to use. With the sky-rf based setups you need at least two different freuqency sets (lower / upper) or you need to tune your antennas to a channel. Anythign else it's shooting in the dark. But, if the antenna performs well enough for your needs, great! Target achived. If not, you have to retry.

Markus

Originally Posted by markus123456

...CP antennas are luckily wideband to a degree, but an antenna having a return loss of say < 20dB at the frequency I intend to use it is really not something suitable for best results.
...
Markus

If I understand correctly, at resonance Hugo is getting 99% of the power with a 20 dB reflection loss and you are getting 99.999% with a 50 dB reflection loss. I think I'd be more concerned with bandwidth or that the power amp isn't operating at spec (95mW instead of the rated 100mW for example) than with the 1% difference between the two antennas. Do you have some other concern?

PS: Nice looking measurement system.

Originally Posted by Dirt-Torpedo

If I understand correctly, at resonance Hugo is getting 99% of the power with a 20 dB reflection loss and you are getting 99.999% with a 50 dB reflection loss. I think I'd be more concerned with bandwidth or that the power amp isn't operating at spec (95mW instead of the rated 100mW for example) than with the 1% difference between the two antennas. Do you have some other concern?

PS: Nice looking measurement system.

You are right. That's the only way to look at things. Thanks for explaining this to me. I'm so glad that I now can stop spend all the effort making as good as possible antennas! :-)

I asume your video link does frequency hopping then. Intersting.

SCNR

Markus

One thing I am noticing is a lot of people are building 5.8GHz antennas with a thick copper wire. This greatly increases the return loss. If the wire diameter exceeds .050" at 5.8GHz the impedance will not converge to proper 1:1 SWR.

When I tune mine, I add solder to the feedpoint for fine tuning. I also leave my feedpoint a bit long to allow for some adjustment if major adjustment is needed.

-Alex

First antenna I've built, going to do a CL next.

Originally Posted by markus123456

...
I asume your video link does frequency hopping then. Intersting. ..Markus

Ah, the great dream for FPV: low latency Spread Spectrum video. I doubt we will see anything with this capability for less than $1000 in the next several years. The primary issue is low latency with all the waveform coding, interleaving and compression/decompression demands.

OMM

Originally Posted by Al Austria

First antenna I've built, going to do a CL next.

Show-off

Excellent build. Either you are a jeweler or this is not really your first antenna.

-Alex

Originally Posted by Old Man Mike

Ah, the great dream for FPV: low latency Spread Spectrum video. I doubt we will see anything with this capability for less than $1000 in the next several years. The primary issue is low latency with all the waveform coding, interleaving and compression/decompression demands.

OMM

I'm working on this. Right now the latency is 420ms, but that's with 720P video. I think with standard 640X480 I might be possible to drop it to maybe 270 ms, but that's still too slow. Working on it...

-Alex

Originally Posted by IBCrazy

Show-off

Excellent build. Either you are a jeweler or this is not really your first antenna.

-Alex

Thanks Alex! I'm pretty new to FPV and that means allot coming from you.

Just got back from flying the antenna, and got a bunch of flights in with it this past weekend as well. Blown away by the performance so far, and I still haven't added a CL to the Tx yet. Thank you for all the info!

Are there any conclusions about this. I built my first this way and was wondering if I should change for my second and having the feedpoint exactly in the center.

Originally Posted by Devonboy

OK - get your idea now.

Only thing I can see is that the elements will be slightly off centred with your method.
I wonder whether this will have a detrimental effect to the CP pattern or not?

From my previous attempts at CP, the slightest deviation or miscalculation and CP is affected.

Both OMM and my builds were with 4 individual elements.

Nontheless, it's good to experiment

Nigel.

I have found that it makes little difference until you get to 5.8GHz. At 2.4GHz the circularity is shifted very slightly, but not much. At 1.3GHz there is no discernable difference.

-Alex

Haven't managed any tests yet, hope it works, soldering isn't brilliant.

Thanks for the design !!

Your soldering looks good. I think that antenna will perform very well for you.

-Alex

how is everyone straightening their mig wire? i have the really "thin" 22.5mil wire for 5.8g.

mine seems a little springy and it just coils back i tried stretching with pliers. then i tried using the drill/twist method, which seems to work except for a small spiral in the wire here and there.

just curious if there is a simpler method? a search on the web usually describes thinner "jewelry" wire (stretch) or thicker mig/copper/steel wire (twist).

thanks!

I made a special straightening jig with rollers and an adjustable tension wheel like on a mig wleder.

-Alex

I was looking at the numbers for the 1280 mhz example in mm, and was wondering if this was done on purpose, or there is an error.

the entire wire length is 469.8mm
quarter length 60mm

first step is to bend up a 1/4 wave length on each end, that is 60mm bent up on each end, leaving 349.8 in the middle.

next step is to bend 2 X 1/4 wave length from the first bends. This is 120mm in from each last bend, leaving 109.8 in the middle.

This means that the "ground legs" will be 54.9 mm, and the "signal legs" are 60mm.

I was thinking these "legs" were going to be the same length, are they supposed to be different?

(likely so, just checking )

Originally Posted by yzguy

I was looking at the numbers for the 1280 mhz example in mm, and was wondering if this was done on purpose, or there is an error.

the entire wire length is 469.8mm
quarter length 60mm

first step is to bend up a 1/4 wave length on each end, that is 60mm bent up on each end, leaving 349.8 in the middle.

next step is to bend 2 X 1/4 wave length from the first bends. This is 120mm in from each last bend, leaving 109.8 in the middle.

This means that the "ground legs" will be 54.9 mm, and the "signal legs" are 60mm.

I was thinking these "legs" were going to be the same length, are they supposed to be different?

(likely so, just checking )

I make an occasional error when computing from time to time going from english to metric. The truth is that so long as the loop length is right, the length of the legs vs the arc really doesn't matter.

-Alex

RG-58 question. I'm sourcing some RG-58 coax to build some CP antennas. I found a less expensive RG-58 A/U at the local electronics store (a couple of bucks for a 6' length). It has a PVC jacket, but is still 50 ohm coax. I also found some RG-58/U (plenum) cable that is more expensive, but I'd have to order it. From the research I've done, the A/U stuff seems to be for 'networking' while the /U stuff is for networking and RF. Will the A/U work or do I need to go for the /U stuff. I'll be making antennas for 1280MHz.

If you keep the cable short, A/U is fine. Just keep the cable less than 2 feet long and you'll be fine.

-Alex

Originally Posted by IBCrazy

If you keep the cable short, A/U is fine. Just keep the cable less than 2 feet long and you'll be fine.

-Alex

Thanks Alex. I'll give the A/U stuff a try then.

Originally Posted by IBCrazy

I make an occasional error when computing from time to time going from english to metric. The truth is that so long as the loop length is right, the length of the legs vs the arc really doesn't matter.

-Alex

ok, cool.

for anyonme else who cares

this example measurement:
1280MHz = 2.31"/60mm

is really this if you do the calculations yourself (and not just lazy and use the numbers)
1280MHz = 2.31"/58.7mm

but aparently does not matter much anyway

How is RG316, rated max at 3GHz for 5.8GHz usage ?
Is there a minimum length where could still be appropriate ?

Originally Posted by RENATOA

How is RG316, rated max at 3GHz for 5.8GHz usage ?
Is there a minimum length where could still be appropriate ?

It's still ok. Not sure where this max frequency comes from. It works better than trying to make RG58 work. Just keep the run less than 30 cm and the loss is fairly low.

-Alex

Originally Posted by IBCrazy

Not sure where this max frequency comes from.
-Alex

It is the manufacturers who specify the recommended maximum working frequency for RG316.
http://www.emc-rflabs.com/Cable-Asse...ble-RG316.aspx

That said, I use it with very short lengths for my Skew Planars at 5.8GHz.

Nigel.

hey guys, how much performance loss would I have if I put a normal 3dbi omni antenna on my quad and used the skew planar on the receiver? Would that even work? I'm asking because right now I have a CP on the quad but it's incredibly fragile and after a crash the middle glue came off. so now I know it's not going to perform as well and it's getting to be not the exact shape it came in.

Assuming it was a cloverleaf? Why not just bend it back and glue it?

You can use the normal linear omni but it probably won't perform as well as even a slightly misshapen CP omni.

Can I use a 2,4gHz whip antenna from my retired wireless router, to make a 5,8gHz CL, or do I need a 5,8gHz whip antenna to start with?

Originally Posted by kimhey

Can I use a 2,4gHz whip antenna from my retired wireless router, to make a 5,8gHz CL, or do I need a 5,8gHz whip antenna to start with?

That will be ok. Both antenna types use 50 Ohm cables and SMA-RP or SMA connectors. Just make sure that the connector type matches your video transmitter and or reciver. Note, you always need a pair of CP antennas, so you have to make a CL for your transmitter and a skew planar wheel (SPW) for your reciver.

HTH

Markus

Originally Posted by markus123456

That will be ok. Both antenna types use 50 Ohm cables and SMA-RP or SMA connectors. Just make sure that the connector type matches your video transmitter and or reciver. Note, you always need a pair of CP antennas, so you have to make a CL for your transmitter and a skew planar wheel (SPW) for your reciver.

HTH

Markus

Thanks! Can't wait to try these CL/SPW antennas.

Alex,

I have found a combination which resists multipathing very well.

SPW on Vtx, and Helical on Vrx.




I discovered it when I was running the FPV summit next to chainlink fences and under trees... The cloverleaf was multipathing severely,
so that combination resolved it.


On the Skywalker I was getting some multipathing
when flying next to the rock cliffs. I tested this combination today
with great success.


-Mike

Originally Posted by m_beeson

Alex,

I have found a combination which resists multipathing very well.

SPW on Vtx, and Helical on Vrx.




I discovered it when I was running the FPV summit next to chainlink fences and under trees... The cloverleaf was multipathing severely,
so that combination resolved it.


On the Skywalker I was getting some multipathing
when flying next to the rock cliffs. I tested this combination today
with great success.


-Mike

It's uncommon to fit a SPW on the plane and a helix on the ground, was the helix pointing to the direction of the plane or straight up with a diversity and another SPW or CL ?

Originally Posted by lrrps

It's uncommon to fit a SPW on the plane and a helix on the ground, was the helix pointing to the direction of the plane or straight up with a diversity and another SPW or CL ?

Helical is a tracking set-up.

I have a omni setup on diversity,
but I can't get good video quality from that one over a mile out.
I'm still working on that antenna,
but the SPW/Helical is a great combo...


-Mike

Alex will admit that the cloverleaf is not the best at producing circularity compared to the skew-planar.
For multipath rejection, circularity is the best tool for combatting multipath reflections.

A helical produces (and receives) circularly polarised signals the best (but is directional).

So, a combination of skew-planar on the VTx and helical on the Rx is the best for tracking enabled systems.

For 'close in' work (omni direcional signals and no tracker), a skew-planar on the VTx and the VRx will be the best for multipath rejection.

Nigel.

When mutipathing is a serious problem, I'd prefer a skew wheel on the TX and a helical on the RX as well. The cloverleaf is an aerial antenna. Ground vehicles will generally beneift from the skew wheel being on the TX side. Airplanes usually do not.

The reason is that the circularity of the cloverleaf is not consistent. It has areas where it's rejection is far better than the skew wheel. However, it also has areas where it is not as good...

I do have another antenna called the Pentalobe sphere which appears to be better than both the clover and the SPW. Unfortunately it's not so form friendly...

-Alex

Originally Posted by IBCrazy

When mutipathing is a serious problem, I'd prefer a skew wheel on the TX and a helical on the RX as well. The cloverleaf is an aerial antenna. Ground vehicles will generally beneift from the skew wheel being on the TX side. Airplanes usually do not.

The reason is that the circularity of the cloverleaf is not consistent. It has areas where it's rejection is far better than the skew wheel. However, it also has areas where it is not as good...

I do have another antenna called the Pentalobe sphere which appears to be better than both the clover and the SPW. Unfortunately it's not so form friendly...

-Alex

Another advantage of the CL is the non-uniform radiation pattern. Point one of the lobe forward to guarantee good video on the way back. The windmill does the same thing, however its opposite polarization rejection either as good as the SPW or better in some areas.

-Hugo

Originally Posted by Hugeone

Another advantage of the CL is the non-uniform radiation pattern. Point one of the lobe forward to guarantee good video on the way back. The windmill does the same thing, however its opposite polarization rejection either as good as the SPW or better in some areas.

-Hugo

I think the windmill has 5 lobes. I have been unable to test it.

I don't think I was able to get your measurements.

"So far" for the airplane I have found that I like the Skewed Planar Wheel for Multipath rejection.

I am still looking for the ground station omni antenna which works best for my

setup.


and I enjoy testing antennas, trying to find better performance.

I think the windmill has 5 lobes. I have been unable to test it.

The windmill have 3 lobes, just like the CL.

I am still looking for the ground station omni antenna which works best for my

setup.

Have you tried the "turbine?

-Hugo

Originally Posted by Hugeone

The windmill have 3 lobes, just like the CL.



Have you tried the "turbine?

-Hugo

Hugo,

I moved this discussion to your thread.


http://www.rcgroups.com/forums/showp...&postcount=294

Thank You

-Mike

Hugo,

Thank you for your help. I will be building more of your antennas and I will post the results (on your thread) when I get good tests finalized. My previous experience leads me to believe that your suggested combo will be successful.


Alex,

Here is today's flight using the SPW and Helical combo.

At the first of this video I am flying next to the rocks which give me multipath issues.

With the SPW I get almost no multipathing.


-Mike

FPV Utah, December 2 2011 (4 min 39 sec)

My new portable ground station, works good!!

Originally Posted by RaptorAP

My new portable ground station, works good!!

that is EXACTLY what i plan to do

I see the 910mhz circ. polarized omni set on the website. Does anyone have a pic of the 910mhz antenna at all with anything for size comparison?

I'll take one of my SPW when I get home, but it's about 6-7 inches across I'd say.

EDIT: this is a CL, but the dimensions should be similar.