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Apr 27, 2014, 06:34 AM
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civicex5speed's Avatar
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Question

*New* SpiroNet


Hi Friends,
I recently ordered a set to SpiroNet RP-SMA antenna's from hobbywireless. I got them quickly and with out any fuss, however when I got them I found BOTH antenna where 4 lobe and NOT 1x 3lobe (VTX) and 1x 4 lobe (VRX)as noted in the description.

My concern is, that after reading so much about the critical nature of antenna's more so with such a high frequency of 5.8 ghz. I'm not sure I want to keep the antenna's.

Hobbywireless quickly followed up with my concerns and advised:
"Hello, the description incorrect. The antennas have been redesigned with the same number of lobes on each and can be used interchangeably. I will notify our webmaster Monday to correct the description."

Should I return them and get a set of the boscams? I don't believe the BlueBeams can be bought with the RP-SMA.

Thanks for the input.
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Apr 27, 2014, 09:23 AM
quadiger
so what's the problem? the updated spironets are now both four lobe skews. It's been said time and time again that the 4 wheel skews perform better as a tx or rx than the clovers. The only reason they used a 3 wheel on the tx was because it was lighter and more aerodynamic but that only really applies to the larger uncovered 1,3g antennas.
Last edited by bimdas; Apr 27, 2014 at 10:04 AM. Reason: keep getting tx and rx mixed up
Apr 27, 2014, 11:29 AM
Registered User
civicex5speed's Avatar
Thread OP
Well, I'm concerned that a 3 lobe cloverleaf is better as a transmitter antenna then a 4 leaf.
From Thread by IBcrazy:
https://www.rcgroups.com/forums/show....php?t=1388264
He notes:
"The best CP TX antenna: I give you the CloverLeaf antenna. Similar to the skew planar wheel, this antenna has one less lobe to it and is arranged at 120 degree angles. This allows the antenna to achieve better SWR (I got a perfect 1.0 on the first try!) compared to the Skew planar wheel’s best SWR of 1.2"
I am not sure that a 3 lobe is for aerodynamic use vs a 4 lobe, I'd use a half wave stick of wire if aerodynamics was a goal.

Indeed the 4 lobe works, but would a 3 lobe be worth the effort?

Thanks bimdas
Apr 27, 2014, 11:34 AM
quadiger
I've found this thread on fpvlabs to be very informative about antennas. http://fpvlab.com/forums/showthread....0-myths-busted.

More specifically as quoted from circana (circular wireless)
"4. THE NUMBER OF LOBES HAS A HUGE IMPACT ON PERFORMANCE
FALSE. The Skew Planar basic concept works for any number of lobes equal or bigger than 3. With 3 lobes the uniformity of the radiation pattern and the axial ratio in the XY plane is slightly affected, but it works. With 4 lobes you achieve almost perfect uniformity in the XY plane. Anything above that (5, 6, 12 lobes) just adds nothing in terms of performance."

If you find the time, read through the thread and you'll see replies from guys like sassan, the guy who designed and sells the spironets, and other dudes like ibcrazy, confirming what he is saying.

You'll also learn why the first version of spironets came with one 3 lobes. Here's a quote from sassen.

"It had to do with the stamping and folding mostly.

Part of it was that we had a problem with the 4-leaf stamping, to get the dimensions of the finished antenna correct on something stamped from a flat sheet and then folded is not trivial. We could make the 3-leaf work without much effort, so this was a risk-free way to get the things produced. Once a batch of the 3-leaf was made we invested time in the 4-leaf, and figured out how to get it made properly and consistently. Since the FPV world had been programmed to accept 3-leaf on the Vtx, and 4-leaf on the Vrx, we decided to introduce like that, also to recuperate some of the tooling and material costs.

During this time we also perfected the tool which bends, and spot-welds, so that the 4-leaf takes just as long as the 3-leaf to assemble. These 4-leaf antennas really take a few seconds to be bent and spot welded now to our exacting specifications. Now that the 4-leaf design is working well we will ramp up production for that and just stick with the 4-leaf SPW both ends and discontinue the 3-leaf."
Last edited by bimdas; Apr 27, 2014 at 11:48 AM.
Apr 27, 2014, 12:18 PM
Registered User
civicex5speed's Avatar
Thread OP
I'm off to read more in the lab....
Thank you very much bimdas
Apr 27, 2014, 12:31 PM
quadiger
Quote:
Originally Posted by civicex5speed
I'm off to read more in the lab....
Thank you very much bimdas
No worries. I've been learning about this fpv stuff too for less than a year. At first everything seemed so complicated but now's come the time for less reading and more building and flying for me.
May 04, 2014, 11:02 AM
Engineer for Christ
IBCrazy's Avatar
Quote:
Originally Posted by civicex5speed
Hi Friends,
I recently ordered a set to SpiroNet RP-SMA antenna's from hobbywireless. I got them quickly and with out any fuss, however when I got them I found BOTH antenna where 4 lobe and NOT 1x 3lobe (VTX) and 1x 4 lobe (VRX)as noted in the description.

My concern is, that after reading so much about the critical nature of antenna's more so with such a high frequency of 5.8 ghz. I'm not sure I want to keep the antenna's.

Hobbywireless quickly followed up with my concerns and advised:
"Hello, the description incorrect. The antennas have been redesigned with the same number of lobes on each and can be used interchangeably. I will notify our webmaster Monday to correct the description."

Should I return them and get a set of the boscams? I don't believe the BlueBeams can be bought with the RP-SMA.

Thanks for the input.
Attachment 6716922
Whatever you do, do NOT buy the DJI/Boscam antennas. They are terrible! The BlueBeams come with RPSMA adapters in the package so they fit all tx/rx systems.

The truth of the matter in the number of lobes comes to lobe geometry. Proper geometry is much more critical than the number. When I went to the Mad Mushroom I found 4 lobes was insufficient for proper pattern due to the change in geometry.

The above stated, the geometry of the SpiroNets leaves much to be desired. There are a few flaws in their design which I have no desire to instruct them on how to correct.

-Alex
May 05, 2014, 04:30 AM
Registered User
Hey IB, sorry, have to jump in here, but hope you don't mind me asking for the user-visible effects of the 'flaws in the design'. We have compared the spironets with many other CP antennas, not looking at the design, but by looking at real-world performance, and these 'flaws' don't seem to be so much of an issue.
(Several thousand sales of these antennas per month, with zero complaints, kindof backs up these results).



Quote:
Originally Posted by IBCrazy
Whatever you do, do NOT buy the DJI/Boscam antennas. They are terrible! The BlueBeams come with RPSMA adapters in the package so they fit all tx/rx systems.

The truth of the matter in the number of lobes comes to lobe geometry. Proper geometry is much more critical than the number. When I went to the Mad Mushroom I found 4 lobes was insufficient for proper pattern due to the change in geometry.

The above stated, the geometry of the SpiroNets leaves much to be desired. There are a few flaws in their design which I have no desire to instruct them on how to correct.

-Alex
May 05, 2014, 05:16 AM
Registered User
Just my 2 cents here... the 3 vs. 4 lobe discussion has generated much 'buzz' on the forums. We did start shipping the SpiroNETs using the 3 lobe antenna, but decided that it just didn't perform as well as the 4 lobe. The radiation pattern has some nasty holes that result in dropouts where you don't expect them, and the whole 'works better as a tx antenna' is kindof questionable...
We did do some pretty serious testing, in both the Tx and Rx configuration (where the only real difference is different complex impedance looking into the SMA, which varies from Tx to Tx, and Rx to Rx anyway), and the 4 is a much nicer beast.

2 cents over :-)



Quote:
Originally Posted by civicex5speed
Well, I'm concerned that a 3 lobe cloverleaf is better as a transmitter antenna then a 4 leaf.
From Thread by IBcrazy:
https://www.rcgroups.com/forums/show....php?t=1388264
He notes:
"The best CP TX antenna: I give you the CloverLeaf antenna. Similar to the skew planar wheel, this antenna has one less lobe to it and is arranged at 120 degree angles. This allows the antenna to achieve better SWR (I got a perfect 1.0 on the first try!) compared to the Skew planar wheel’s best SWR of 1.2"
I am not sure that a 3 lobe is for aerodynamic use vs a 4 lobe, I'd use a half wave stick of wire if aerodynamics was a goal.

Indeed the 4 lobe works, but would a 3 lobe be worth the effort?

Thanks bimdas
May 05, 2014, 07:18 AM
Registered User
civicex5speed's Avatar
Thread OP
Thanks for the input on this matter here. I have tested the Spironets to about 1200 feet, keep in mind this is a Boscam setup, 600mw TX and NOT in the air, but across a field
I used a wifi signal app on my phone, it can read 2.4ghz and 5.8ghz to see about noise in the area, there was nothing found. I have no idea if this means anything at all. also, it's a more rural area for what it's worth. Does 1200 feet seam reasonable?

I plan to go to 2.4ghz or 1.2 for video when I know what I'm doing better.


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