Thread Tools
Old Feb 01, 2011, 06:19 PM
Blue Chip is offline
Find More Posts by Blue Chip
Honey Badger
Blue Chip's Avatar
United States, FL
Joined Oct 2005
1,814 Posts
Discussion
433mhz DIY antennas: Material Q

What are you guys using for the wire for an antenna? Does it really matter?

I saw the ones that Trappy and Sander made. However - my 90 degree connector doesn't have the diameter to run the plastic sleeve inside of the 90... does it matter what the thickness of the wire is? Solid strand (like a V antenna) or can it be similar to that of the 72mhz wire?
Blue Chip is offline Find More Posts by Blue Chip
Reply With Quote
Sign up now
to remove ads between posts
Old Feb 01, 2011, 07:14 PM
EDI PAULO is offline
Find More Posts by EDI PAULO
Registered User
EDI PAULO's Avatar
DANBURY CT.
Joined Apr 2010
228 Posts
Quote:
Originally Posted by Blue Chip View Post
What are you guys using for the wire for an antenna? Does it really matter?

I saw the ones that Trappy and Sander made. However - my 90 degree connector doesn't have the diameter to run the plastic sleeve inside of the 90... does it matter what the thickness of the wire is? Solid strand (like a V antenna) or can it be similar to that of the 72mhz wire?
This is the one i use on my DL receiver antenna:

http://www.l-com.com/productfamily.aspx?id=63

Edi
EDI PAULO is offline Find More Posts by EDI PAULO
Reply With Quote
Old Feb 01, 2011, 10:42 PM
mike20sm is offline
Find More Posts by mike20sm
Registered User
mike20sm's Avatar
California
Joined Aug 2010
161 Posts
I think Trappy said to use servo wire, which happens to be stranded. I just got my 90 degree SMA connectors and will be making my antennas too.
mike20sm is offline Find More Posts by mike20sm
Reply With Quote
Old Feb 02, 2011, 06:11 AM
IBCrazy is online now
Find More Posts by IBCrazy
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
11,712 Posts
As long as the wire is metal, it doesn't matter. Stranded, solid, copper, zince, steel, covered, or bare. It doesn't matter.

-Alex
IBCrazy is online now Find More Posts by IBCrazy
RCG Plus Member
Old Feb 02, 2011, 06:14 AM
Blue Chip is offline
Find More Posts by Blue Chip
Honey Badger
Blue Chip's Avatar
United States, FL
Joined Oct 2005
1,814 Posts
I only want it to touch the center pin though - correct?
Blue Chip is offline Find More Posts by Blue Chip
Reply With Quote
Old Feb 02, 2011, 06:54 AM
IBCrazy is online now
Find More Posts by IBCrazy
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
11,712 Posts
No, you need to make a dipole: http://www.rcgroups.com/forums/showt...php?t=1159968\
IBCrazy is online now Find More Posts by IBCrazy
RCG Plus Member
Old Feb 02, 2011, 07:53 AM
TheWhiteSheep is offline
Find More Posts by TheWhiteSheep
Suspended Account
Joined Feb 2011
12 Posts
no, you don't need to make a dipole at all. the monopole works to ~120km (90 miles) with the EzUHF (that's with margin, 180km / 120 miles without margin). the dipole will give you further range ... but I have a feeling you won't need it.

multi-strand won't wear as fast, therefore is the suggested way. single-strand works as well but I wouldn't fly with one.
TheWhiteSheep is offline Find More Posts by TheWhiteSheep
Reply With Quote  (Disabled)
Old Feb 02, 2011, 07:53 AM
Blue Chip is offline
Find More Posts by Blue Chip
Honey Badger
Blue Chip's Avatar
United States, FL
Joined Oct 2005
1,814 Posts
The only problem with that it I will be using 2 antennas on the EZUHF - and need them to come out of a 90.... I can only go "up" not "up and down."

This is not a dipole is it? I believe this is similar to the one that Sander and Jeff both built...
http://www.rcgroups.com/forums/showp...&postcount=613

Sorry for the newb questions....
Blue Chip is offline Find More Posts by Blue Chip
Reply With Quote
Old Feb 02, 2011, 08:01 AM
TheWhiteSheep is offline
Find More Posts by TheWhiteSheep
Suspended Account
Joined Feb 2011
12 Posts
no, that's not a dipole. dipole would touch the ground at some point. dipoles are better, but you seem to have the same problem as me - and pretty much everyone else that puts the antenna where it belongs - that you can't go down. therefore the monopole is the best choice.
TheWhiteSheep is offline Find More Posts by TheWhiteSheep
Reply With Quote  (Disabled)
Old Feb 02, 2011, 08:12 AM
boopidoo is offline
Find More Posts by boopidoo
On a holiday?
boopidoo's Avatar
Uppsala, Sweden
Joined Sep 2008
4,168 Posts
Do monopole and dipole react to RFI the same way? Will a dipole pick up more RFI?
boopidoo is offline Find More Posts by boopidoo
Reply With Quote
Old Feb 02, 2011, 10:23 AM
IBCrazy is online now
Find More Posts by IBCrazy
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
11,712 Posts
Quote:
Originally Posted by Blue Chip View Post
The only problem with that it I will be using 2 antennas on the EZUHF - and need them to come out of a 90.... I can only go "up" not "up and down."

This is not a dipole is it? I believe this is similar to the one that Sander and Jeff both built...
http://www.rcgroups.com/forums/showp...&postcount=613

Sorry for the newb questions....
That's a 1/4 wave zepp antenna. The problem with using a 1/4 wave antenna is that it isn't as efficient as a dipole. Let me explain:

The RX is looking for an impedance of 50 Ohms. A 1/4 wave Zepp is about 39 ohms or so. A dipole is about 50 Ohms (actually a bit more). The closer you are to the proper impedance, the lower your SWR and the better the antenna matches the transmitter/receiver.

Now the other thing to consider is radiation efficiency. 1/4 wave zepp antenna generat an incomplete artificial ground plane. When placed above a groung plane, they do much better, but the radiation efficiency is significantly reduced when there is no ground plane available. Theoretically you lose ~3db but in actuality it's more like 1.5-2db or so. The dipole needs no ground plane as the counterpoise generates the other half of the radiation pattern.

-Alex
IBCrazy is online now Find More Posts by IBCrazy
RCG Plus Member
Old Feb 02, 2011, 10:24 AM
IBCrazy is online now
Find More Posts by IBCrazy
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
11,712 Posts
Quote:
Originally Posted by TheWhiteSheep View Post
no, that's not a dipole. dipole would touch the ground at some point. dipoles are better, but you seem to have the same problem as me - and pretty much everyone else that puts the antenna where it belongs - that you can't go down. therefore the monopole is the best choice.
90 degree inverted Vee... That fixes the orientation problem.

-Alex
IBCrazy is online now Find More Posts by IBCrazy
RCG Plus Member
Old Feb 02, 2011, 10:33 AM
TheWhiteSheep is offline
Find More Posts by TheWhiteSheep
Suspended Account
Joined Feb 2011
12 Posts
Quote:
Originally Posted by IBCrazy View Post
90 degree inverted Vee... That fixes the orientation problem.

-Alex
nope, a Vee still has something sticking out the bottom. what I have works and is very practical. it may not be the most efficient, but when (and if) I ever reach the limit of my range I will certainly investigate better antennas
TheWhiteSheep is offline Find More Posts by TheWhiteSheep
Reply With Quote  (Disabled)
Old Feb 02, 2011, 10:39 AM
IBCrazy is online now
Find More Posts by IBCrazy
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
11,712 Posts
I was thinking he could simply solder a 1/4 wavelength element to the crimp terminal and extend the center pin out 1/4 wave as well 90 degrees to the pin. That would be a decent Vee antenna with good swr match.

Also, thicker antennas are technically more efficient. The reactive components are much smaller in a thicker antenna. I plan to use 24 or 26 AWG wire for my DragonLink antennas. However I also plan to use a turnstile antenna for the DragonLink.

-Alex
IBCrazy is online now Find More Posts by IBCrazy
RCG Plus Member
Old Feb 02, 2011, 11:28 AM
Pepelatz is offline
Find More Posts by Pepelatz
Registered User
Pepelatz's Avatar
Staten Island, NY, USA
Joined Aug 2006
286 Posts
deleted
Pepelatz is offline Find More Posts by Pepelatz
Last edited by Pepelatz; Feb 02, 2011 at 11:40 AM.
Reply With Quote


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion 433MHz / 70cm Yagis ... WHERE?! trappy FPV Talk 35 Mar 24, 2014 06:10 AM
Sold Set of 433mhz SMA antenae Blue Collar FPV Equipment (FS/W) 3 Dec 11, 2010 11:39 AM
Discussion Dragonlink 433Mhz signal Yagi Autotracking? ganapati08 FPV Talk 5 Oct 24, 2010 02:25 PM
Discussion 433mhz vario system adi91 Eagle Tree Systems 1 Oct 11, 2010 07:51 PM
EP Concept tailrotor q's and DIY rotor q's Scott Coombe Electric Heli Talk 2 May 25, 2003 10:25 PM