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Old May 09, 2011, 07:53 AM
Engineer for Christ
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Amherst, VA
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A 6 turn helical has a pretty narrow beam. It also has a very strange shap to it. However it shouldn't be any narrower than the BiQuad's.

-Alex
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Old May 09, 2011, 07:54 AM
Engineer for Christ
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Amherst, VA
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Quote:
Originally Posted by LexusFPV View Post
whakahere

hello Whakahere, I've ask a few questions on your other thread.

is it really possible to achieve 8-10km using Foxtech 5.8ghz 200mW VidTx using IBcrazy Clover Leaf antenna,

and now using a 5-6 turn Helical on a 5.8ghz VidRx?
Yes. Not easily, though. I can be done. 4 turns is enough. Use the hecker transformer to match it.

-Alex
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Old May 09, 2011, 02:05 PM
Kiwi in Germany
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Germany
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I haven't run any tests as of yet as I want to set up diversity with it just in case. I will be shocked if I reach 8km on it but since I have made 3km just on a spw and a cl I think anything is possible The only way to find out is to try it. I want diversity first as I want to at least have some back up just in case. how narrow is it?

So 6 turns are too many ...umm well I will give it a go and if I find it is too much I will just limit the turns on my next build.
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Old May 09, 2011, 02:14 PM
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Canada,Quebec
Joined Jan 2005
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Quote:
Nice build Hugo. What wire gauge did you use? 10 and 12AWG work best in my experiments for 2.4GHz.

Also, how are you planning on tununig that beast?

-Alex
I taken my helical to the telecom lab today, the spectrum analyzer gave 1.3:1
The tech there soldered a small piece of metal to my matching strip and by bending it a bit he reached 1.05:1
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Old May 09, 2011, 05:13 PM
Registered User
SW England
Joined Aug 2009
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Has nobody yet used the gamma matching of a Helical?

(scroll down about half way to the part about the W0OQC mathing method)
http://www.safe-pc.net/helical.html
http://www.safe-pc.net/images/helix2.gif
http://webpages.charter.net/wk4r/2400/ant1a.jpg

Super easy to make and matches well

Go on, you know you want to !

Nigel.
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Old May 09, 2011, 08:36 PM
DragonLINK UHF only!!!!
Joined Feb 2011
1,217 Posts
I have the Foxtech 5.8ghz 200mW VidTx with Clover Leaf,
and I'm using the Foxtech AOI goggles with built in VidRx, I have the
Skewer Planar Wheel on the AOI goggles.....

(no heavy groundstation to lug around).

I will try and use the Diversity with the 4 turn Helical for longer distances (~8km and up).

I'm hoping to test it out on my SkyWalker, I'm just waiting for my 4s 5000mah
to come from HobbyKing..... I'm all ready to go, minus 4s Flight Lipos'.


I hope IBCrazy and Markus are right, ......
I'm hoping to get 3km (2 miles) and I'm happy
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Old May 10, 2011, 07:38 AM
Engineer for Christ
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Amherst, VA
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Quote:
Originally Posted by Devonboy View Post
Has nobody yet used the gamma matching of a Helical?

(scroll down about half way to the part about the W0OQC mathing method)
http://www.safe-pc.net/helical.html
http://www.safe-pc.net/images/helix2.gif
http://webpages.charter.net/wk4r/2400/ant1a.jpg

Super easy to make and matches well

Go on, you know you want to !

Nigel.
I tried a gamma match. I didn't like it. It was simply too difficult to get right and was very fickle. I use the tapered microstrip match. It's simple and it works. It's the most tolerant of error as well.

-Alex
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Old May 10, 2011, 12:10 PM
Yes, "that" Karl...
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Canada, BC, Burnaby
Joined Mar 2007
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Now I HAVE to build one for my setup...
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Old May 14, 2011, 11:14 PM
Singapore
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Singapore
Joined Oct 2007
53 Posts
I've been cracking my head really hard how do i make a rounded reflector for the helical antenna snice i do not have any machines around to cut a nice circle shape.

So i went down to a bakery store and found some 7-1/4 diameter aluminium pie dishes... its going to give me a hard time to snip off the rounded edges of the pie dish because its made of a pretty thick aluminium sheet.

Do anyone have an answer whether the singal be affected in anyways if i leave the rounded edge of the aluminium pie dish on?
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Old May 14, 2011, 11:43 PM
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Louisiana
Joined Oct 2005
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Quote:
Originally Posted by viper1990 View Post
I've been cracking my head really hard how do i make a rounded reflector for the helical antenna snice i do not have any machines around to cut a nice circle shape.

So i went down to a bakery store and found some 7-1/4 diameter aluminium pie dishes... its going to give me a hard time to snip off the rounded edges of the pie dish because its made of a pretty thick aluminium sheet.

Do anyone have an answer whether the singal be affected in anyways if i leave the rounded edge of the aluminium pie dish on?
Should work. Mount it to the bottom (the side your measuring tape is on). It's a reflector, so anything behind that surface will not have an appreciable effect. You just don't want anything sticking out towards the driven element (helix).
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Old May 15, 2011, 12:20 AM
Singapore
viper1990's Avatar
Singapore
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Thankyou sawman for that super quick reply.

I'm building the helical antenna right now as we speak and i'll post my results as soon as i test it!
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Old May 15, 2011, 11:19 AM
Engineer for Christ
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Amherst, VA
Joined Jun 2006
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Quote:
Originally Posted by viper1990 View Post
I've been cracking my head really hard how do i make a rounded reflector for the helical antenna snice i do not have any machines around to cut a nice circle shape.

So i went down to a bakery store and found some 7-1/4 diameter aluminium pie dishes... its going to give me a hard time to snip off the rounded edges of the pie dish because its made of a pretty thick aluminium sheet.

Do anyone have an answer whether the singal be affected in anyways if i leave the rounded edge of the aluminium pie dish on?
Placing it inside the dish will actually help control side lobe radiation. It might be a benefit if you don't usually fly far out to the sides.

-Alex
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Old May 15, 2011, 02:08 PM
Registered Loser :)
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New Zealand
Joined Sep 2009
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I was wondering what happens if you use a reflector which is way too big?
I am using a 6 turn 1010mhz helical with my computer case door as the reflector. It has worked really well and I was about to get a piece of galv sheet cut the correct size but did not want to lose any performance. Would the correct size work better for long distance or the oversize one?




Mark
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Old May 15, 2011, 02:13 PM
Kiwi in Germany
whakahere's Avatar
Germany
Joined Jun 2010
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Quote:
Originally Posted by mark hitchman View Post
I was wondering what happens if you use a reflector which is way too big?
I am using a 6 turn 1010mhz helical with my computer case door as the reflector. It has worked really well and I was about to get a piece of galv sheet cut the correct size but did not want to lose any performance. Would the correct size work better for long distance or the oversize one?




Mark
god damn you are such a kiwi!! ... um but one mistake I see is no number 8 wire. I thought you were a cow cocky?

From what I have read the circle shape helps prevent the signal from bleeding out the sides as much. (but I could be way off base here).
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Old May 15, 2011, 04:03 PM
Registered Loser :)
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New Zealand
Joined Sep 2009
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Quote:
Originally Posted by whakahere View Post
god damn you are such a kiwi!! ... um but one mistake I see is no number 8 wire. I thought you were a cow cocky?

From what I have read the circle shape helps prevent the signal from bleeding out the sides as much. (but I could be way off base here).
I am actually a refrigeration engineer We moved out of the city onto 4 acres to have a bit of space. We have a total of 3 cows although the freezer is starting to get a bit low so that may be down to 2 soon

Yeah I thought I might cut a round one but I am not sure if I make it smaller like it's meant to be if I will lose some range, I suppose I should experiment a bit aye.

Mark
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