HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old May 23, 2011, 10:46 PM
Registered User
Old Man Mike's Avatar
Joined Sep 2007
1,803 Posts
Quote:
Originally Posted by careyer View Post
Hi there

i've build one of those Skew Planar Wheel for my 910Mhz 800mw Hobbyking RX/TX Set but the result is extremely bad. ...
That antenna looks too small for 910 Mhz, more like a 1280 Mhz antenna. What dimensions did you use?

OMM
Old Man Mike is offline Find More Posts by Old Man Mike
Reply With Quote
Sign up now
to remove ads between posts
Old May 24, 2011, 12:07 AM
QiW
Registered User
south east asia
Joined Mar 2009
943 Posts
hi OMM ...
if the rx casing is anything to go by (i assume they are the same size as mine) then his antenna size looks about the same as mine
QiW is offline Find More Posts by QiW
Reply With Quote
Old May 24, 2011, 11:12 AM
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
10,060 Posts
Quote:
Originally Posted by careyer View Post
Hi there

i've build one of those Skew Planar Wheel for my 910Mhz 800mw Hobbyking RX/TX Set but the result is extremely bad.

Though i tried to keep tolerances as small as somehow possible (<= 1-2mm) it does not give me more than 200m of range in direct line of sight. Tried all channels 1-4 (910-1040 MhZ) and channel 3 ist best. The Standard antennas even give me slighly more range and more robust signal. Any Idea what might be wrong?

Here's a pic of my two antennas:


P.S: 900M Mhz is the primary band for cellphones right over here. Might this affect the range that much? Cellphones are allowed to send 2W .... basestations about 8W.
I have a hard time seeing from the picture, but it looks to me like one is LHCP and the other is RHCP. The interactions between these antennas will be -18 db or so if this is the case.

-Alex
IBCrazy is offline Find More Posts by IBCrazy
RCG Plus Member
Old May 24, 2011, 11:58 AM
Suspended Account
Joined Dec 2009
330 Posts
...
Mictronics is offline Find More Posts by Mictronics
Last edited by Mictronics; Jul 02, 2012 at 01:37 AM. Reason: Tired of RCG - Quality can be found at FVLAB
Reply With Quote
Old May 24, 2011, 02:55 PM
la fabrique circulaire
terry74's Avatar
geneva
Joined Jan 2008
550 Posts
just to post also here and say that the "magic combo" CP/SPW work like no other antenna....

CL and SPW antenna on my DIY Delta FPV wing (11 min 43 sec)


is this the future standard antenna in FPV ?

yes with no doubt


Jay
terry74 is offline Find More Posts by terry74
Reply With Quote
Old May 26, 2011, 02:12 AM
QiW
Registered User
south east asia
Joined Mar 2009
943 Posts
i am currently running 900mhz SPW on my vrx
to prevent wire clutter around myself ... i have gotten a FOXTECH AIO with built in 5.8 vrx
i then placed a 25mW 5.8vtx to relay the video from my 900mhz system to my goggles

question ...
how would performance compare if i just place the 900 CL on a tripod on the ground vs tripod on the roof of my car/van ?
the height of the tripod would be about 5ft or so
my current fly field is asphalt car park with buildings with some curve and flat metal roofs but these buildings are nothing higher than 3-4 storeys

thanks ...
QiW is offline Find More Posts by QiW
Reply With Quote
Old May 26, 2011, 06:36 AM
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
10,060 Posts
On the ground would be better. Eventhough the Cloverleaf/SPW reject multipath well, placing it on a huge metal reflector will still hurt performance.

-Alex
IBCrazy is offline Find More Posts by IBCrazy
RCG Plus Member
Old May 26, 2011, 07:18 AM
team SSG
crezzee's Avatar
Worcester UK
Joined Nov 2004
712 Posts
Quote:
Originally Posted by IBCrazy View Post
On the ground would be better. Eventhough the Cloverleaf/SPW reject multipath well, placing it on a huge metal reflector will still hurt performance.

-Alex
Not sure i agree Alex.

I have my VRX mounted on a tripod that stands on the roof of my van; 1.2m higher than the roof. I have also tried with the tripod on the ground and have to say it seemed better on the roof.

I have been led to belive that omni antennas work best when they are mounted up as high as possible (up to a point) and this does seem to be the case with my CL, SPW combo.

You can see my setup at the end of this vid (4:52); only close in flying in this clip but i have been out to near my 35MHz range limit and the video was still great

FPV on the beach (5 min 28 sec)
crezzee is offline Find More Posts by crezzee
Reply With Quote
Old May 26, 2011, 08:30 AM
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
10,060 Posts
A stand on the roof is fine, but on the ground is better. Well, assuming the Fresnel zone is clear. I guess I figured that there would be no objects he'd be flying over that would disturb the Fresnel zone.


-Alex
IBCrazy is offline Find More Posts by IBCrazy
RCG Plus Member
Old May 26, 2011, 08:44 AM
QiW
Registered User
south east asia
Joined Mar 2009
943 Posts
i will try both this weekend and let u guys know
there is also a telco GSM 900/1800 200m from where i stand .. hehehehe
QiW is offline Find More Posts by QiW
Reply With Quote
Old May 26, 2011, 04:17 PM
FPV from Lithuania
vipix's Avatar
Lithuania
Joined Mar 2007
128 Posts
Alex, can i put SPW in plastic case with 1mm wall thickness? 5.8Ghz 200mW. I want to build compact ground station and dont want to brake a SPW antenna, so i need to put it in plastic case.
vipix is offline Find More Posts by vipix
Reply With Quote
Old May 27, 2011, 07:50 AM
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
10,060 Posts
Quote:
Originally Posted by vipix View Post
Alex, can i put SPW in plastic case with 1mm wall thickness? 5.8Ghz 200mW. I want to build compact ground station and dont want to brake a SPW antenna, so i need to put it in plastic case.
Yes.
IBCrazy is offline Find More Posts by IBCrazy
RCG Plus Member
Old May 27, 2011, 01:24 PM
Future-proof EVERYTHING
DarkHeli's Avatar
NY
Joined Jul 2008
762 Posts
Spw

How does my SPW look? @ 1280 RH polarized
DarkHeli is offline Find More Posts by DarkHeli
Reply With Quote
Old May 27, 2011, 03:13 PM
Registered User
Toysrme's Avatar
Birmingham, Alabama
Joined Jun 2002
2,966 Posts
lobes are not angled vertically enough & you need to pull them around so there's a more even overlap.

otherwise good.
Toysrme is offline Find More Posts by Toysrme
Reply With Quote
Old May 27, 2011, 08:12 PM
Oh so close!
clipper99's Avatar
Campbell River
Joined Jan 2010
702 Posts
Quote:
Originally Posted by Toysrme View Post
lobes are not angled vertically enough & you need to pull them around so there's a more even overlap.

otherwise good.
Man you got some mad ability for spacial visualization in your brain! I've only built 2 5.8ghz SPW's and it looks like he's got his 45 degrees going on to me but anything other than an oblique angle and it gets hard for me to tell either way!

Cheers
clipper99 is offline Find More Posts by clipper99
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Mini-HowTo DIY Ground Plane omni directional RX antenna IBCrazy FPV Talk 60 Nov 19, 2012 06:11 AM
Discussion 900 mhz circular polarized antenna? g00bd0g FPV Talk 9 Aug 21, 2012 09:54 AM
Discussion Left/Right circular polarized antenna ? SpookiePower FPV Talk 44 Jun 04, 2011 06:41 PM
Discussion 18dbi Circular Polarized Patch ? Coyote64 FPV Talk 3 Nov 10, 2010 04:59 PM
Question Circular polarized antenna question Sov4life FPV Talk 8 Mar 05, 2010 05:00 PM