HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Oct 11, 2012, 02:24 PM
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
10,068 Posts
Anyone who can build a 5.8GHz Crosshair array is a better man than I am. The cable lengths would be so incredibly short that I don't know that it would be possible to phase them.

Helicals are a totally different story. You don't need matching networks for helicals. Why? Simple: you have to match the impedance to the line anyway with your matching stub. Sure you still need to rotate the helical antennas in your array to achieve rotation, but there is no need to use 1/4 wave lines. You can use 1/2 wave lines and adjust the characteristic impedance by moving the matching stub. This is the preferred method so that you ensure your load is purely resistive with respect to the other helicals in the array.

-Alex
IBCrazy is offline Find More Posts by IBCrazy
RCG Plus Member
Sign up now
to remove ads between posts
Old Oct 14, 2012, 06:17 PM
Registered User
Imagecatcher's Avatar
NSW Australia
Joined Mar 2010
245 Posts
Ground post

I didnt have copper tube and after needing so much heat to the gal reflector, I didnt want to solder the braid to it.
Q: is dropping a copper wire from the resonator (where the braid attaches) to the reflector ok?
I have seen it done in an earlier post but I dont recall any feedback from IBC or other as to any down sides.
Imagecatcher is offline Find More Posts by Imagecatcher
Reply With Quote
Old Oct 14, 2012, 09:42 PM
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
10,068 Posts
I really do not know. If it is indeed 1/4 wave long, then it should cancel itself out and work fine. If not, then I really do not know.

-Alex
IBCrazy is offline Find More Posts by IBCrazy
RCG Plus Member
Old Oct 20, 2012, 02:58 AM
60+ = too old ;)
Skipper1952's Avatar
Poland, West Pomeranian Voivodeship, Szczecin
Joined Oct 2010
9 Posts
How about using biquad as TX antenna. It is electrically closed circuit. Is it safe for transmitter?
Skipper1952 is offline Find More Posts by Skipper1952
Reply With Quote
Old Oct 20, 2012, 09:12 AM
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
10,068 Posts
Yes it is safe for a transmitter. I am assuming you are referring to a 2.4GHz radio. This works well for increasing range so long as you are capable of aiming it.

-Alex
IBCrazy is offline Find More Posts by IBCrazy
RCG Plus Member
Old Oct 22, 2012, 04:03 PM
Registered User
willieprinsloo's Avatar
Joined Oct 2007
61 Posts
Quote:
Originally Posted by heinduplessis View Post
Holy smokes that was hard work

Mine did not come out as perfect as some of the others on here at all, but I was wondering if you all could take a look at it and see if I've made a catastrophic error somewhere.

Damn it's hard to solder something to a galvanized plate with a 25W soldering iron...

I couldn't find small nylon screws so I used wooden rods with epoxy.

I've soldered the shielding at the back of the plate in stead of the bottom of the front.
It looks great! Now it's time to test it...
willieprinsloo is offline Find More Posts by willieprinsloo
Reply With Quote
Old Oct 23, 2012, 12:25 PM
Foam Snow
South Africa, WC, Cape Town
Joined Aug 2011
1,289 Posts
Well a huge thank you very much to Alex!

Willie & I just came back from ground tests and on 9.7km the signal was still fine, just some lines and the tiniest hint of noise. See attached.

If this is ground based, maybe I should still have perfect signal at 10km.

My tx is a lawmate 500mw with a home made V.

The stock dipole ducktail dropped out at 3km.

Thanks Alex!!
heinduplessis is offline Find More Posts by heinduplessis
Last edited by heinduplessis; Oct 23, 2012 at 12:33 PM.
Reply With Quote
Old Oct 23, 2012, 12:59 PM
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
10,068 Posts
You will go way farther than 10 km if you are doing 9km on the ground. The ground blocks ~50% of the Fresnel zone at that distance. In the air, the Fresnel zone is clear.

-Alex
IBCrazy is offline Find More Posts by IBCrazy
RCG Plus Member
Old Oct 23, 2012, 01:16 PM
Foam Snow
South Africa, WC, Cape Town
Joined Aug 2011
1,289 Posts
Quote:
Originally Posted by IBCrazy View Post
You will go way farther than 10 km if you are doing 9km on the ground. The ground blocks ~50% of the Fresnel zone at that distance. In the air, the Fresnel zone is clear.

-Alex
Yeah - that football shape beam. I'm just carefully optimistic

I'll know by the weekend..
heinduplessis is offline Find More Posts by heinduplessis
Reply With Quote
Old Oct 25, 2012, 04:27 AM
Foam Snow
South Africa, WC, Cape Town
Joined Aug 2011
1,289 Posts
Quote:
Originally Posted by IBCrazy View Post
You will go way farther than 10 km if you are doing 9km on the ground. The ground blocks ~50% of the Fresnel zone at that distance. In the air, the Fresnel zone is clear.

-Alex
We just did 17km from Table Mountain to Blouberg!! Perfect signal, even better than the 10km ground test!

Long Range FPV Antenae - 30KM (0 min 9 sec)
heinduplessis is offline Find More Posts by heinduplessis
Reply With Quote
Old Oct 25, 2012, 07:30 AM
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
10,068 Posts
^You had a long way to go on that BiQuad. If you are confident your plane can make a longer journey, go for it. The BiQuad rocks. I like it so much that I'm actually ganging 4 of them in a phased array for a professional project of mine.
IBCrazy is offline Find More Posts by IBCrazy
RCG Plus Member
Old Oct 25, 2012, 09:00 AM
throw new IOPilotException();
IceWind's Avatar
Ireland, County Dublin, Dublin
Joined Feb 2005
2,567 Posts
Great!
I'm still pushing the limits of my antenna.

Just out of curiosity what's the power of the vTX you using?
IceWind is offline Find More Posts by IceWind
Reply With Quote
Old Oct 25, 2012, 02:40 PM
Foam Snow
South Africa, WC, Cape Town
Joined Aug 2011
1,289 Posts
Quote:
Originally Posted by IBCrazy View Post
^You had a long way to go on that BiQuad. If you are confident your plane can make a longer journey, go for it. The BiQuad rocks. I like it so much that I'm actually ganging 4 of them in a phased array for a professional project of mine.
Sounds serious I'm just delighted it works so well!

Quote:
Originally Posted by IceWind View Post
Great!
I'm still pushing the limits of my antenna.

Just out of curiosity what's the power of the vTX you using?
500mw lawmate.
heinduplessis is offline Find More Posts by heinduplessis
Reply With Quote
Old Oct 27, 2012, 01:11 AM
Registered User
tushev's Avatar
USA, NY, New York
Joined Nov 2008
1,501 Posts
Tadaaa!! my version is ready to be tested
tushev is offline Find More Posts by tushev
Reply With Quote
Old Oct 27, 2012, 02:33 PM
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
10,068 Posts
Not to 1-up anyone but...

Just finished this bad boy this morning. 17dbic linear phased OctoQuad array.

Phasing network is 2 - 3/4 wave 50 ohm cables.

-Alex
IBCrazy is offline Find More Posts by IBCrazy
RCG Plus Member
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Build Log How To Build a BiQuad RX antenna Talajouy FPV Talk 21 Dec 22, 2010 11:52 PM
Question DIY Biquad antenna for a 900mHz Moosthegoose FPV Talk 5 Jan 14, 2010 03:37 AM
Discussion Antenna tutorial JIMOOO FPV Talk 1 Feb 25, 2007 12:04 AM
Discussion looking for a DIY tutorial. TonyBAMF Beginner Training Area (Aircraft-Electric) 8 Jan 10, 2006 04:56 PM
I need help to DIY flywire antenna for 36 MHZ RX GoodHeli Radios 5 Aug 24, 2003 08:05 PM