Hello all, whats the take on these antennas? I am sure someone on here has used them and they certainly look cool but how do they perform?
Dont you have to switch polerization on a cross polerized yagi?
I know there is not a perfect antenna, just wondering about the Helicoil...
Kevin KF7MYK
What, exactly, is a helicoil antenna?
On 12-Jul-11 00:39, Kevin Deane wrote:
Hello all, whats the take on these antennas? I am sure someone on here has used them and they certainly look cool but how do they perform?
Dont you have to switch polerization on a cross polerized yagi?
I know there is not a perfect antenna, just wondering about the Helicoil...
Kevin KF7MYK _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
A "Helicoil" is a threaded insert used to repair stripped threads.
I think you're asking about a HELICAL antenna.
They work very well, and are easy to build. They're very forgiving in construction errors, but have a few pitfalls you want to watch out for.
You do NOT want to wind one on PVC pipe for a support, as the dielectric constant of the PVC will throw off the antenna from the design numbers you use to wind the "coil".
This type of helical is called an "Axial Mode" antenna. A "Normal Mode" helical is how a rubber duck is made, and is not what you want.
The ARRL Antenna Handbook has several designs that work well, and there's a TON of information on the Web about building an "Axial Mode Helical Antenna".
They're fixed polarization, determined when you wind it, and the only way to switch between left-hand and right-hand is to have another antenna, and switch to it.
I've built several, and they work pretty well. They get pretty big at 2 Meters, but are manageable (at least for me!) at 70cm and up.
73, Jim KQ6EA
On 07/12/2011 12:39 AM, Kevin Deane wrote:
Hello all, whats the take on these antennas? I am sure someone on here has used them and they certainly look cool but how do they perform?
Dont you have to switch polerization on a cross polerized yagi?
I know there is not a perfect antenna, just wondering about the Helicoil...
Kevin KF7MYK _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
I second Jim's assessment here. Helical antennas are the only way I will build an antenna at 1.2 ghz or higher. It's not worth the stress trying to measure things to the precision needed for a Yagi at those frequencies. The less stress (and time) taken to build the antenna, the more enjoyment you will get from actually using it!
For 2m and 70cm, Yagis are good, but also consider making a Quad or a Quagi (a 2 element Quad with more Yagi elements in front). I used a home-built 8 element Quagi from the ARRL Antenna Handbook for several years as a satellite antenna, until I found a crossed Yagi antenna at a Ham Swap for a price I couldn't pass up. Still have the Quagi, just in case.
Greg KO6TH
Date: Tue, 12 Jul 2011 01:38:17 +0000 From: kq6ea@verizon.net To: amsat-bb@amsat.org Subject: [amsat-bb] Re: 70cm Helicoil Good/Bad expensive?
A "Helicoil" is a threaded insert used to repair stripped threads.
I think you're asking about a HELICAL antenna.
They work very well, and are easy to build. They're very forgiving in construction errors, but have a few pitfalls you want to watch out for.
You do NOT want to wind one on PVC pipe for a support, as the dielectric constant of the PVC will throw off the antenna from the design numbers you use to wind the "coil".
This type of helical is called an "Axial Mode" antenna. A "Normal Mode" helical is how a rubber duck is made, and is not what you want.
The ARRL Antenna Handbook has several designs that work well, and there's a TON of information on the Web about building an "Axial Mode Helical Antenna".
They're fixed polarization, determined when you wind it, and the only way to switch between left-hand and right-hand is to have another antenna, and switch to it.
I've built several, and they work pretty well. They get pretty big at 2 Meters, but are manageable (at least for me!) at 70cm and up.
73, Jim KQ6EA
On 07/12/2011 12:39 AM, Kevin Deane wrote:
Hello all, whats the take on these antennas? I am sure someone on here has used them and they certainly look cool but how do they perform?
Dont you have to switch polerization on a cross polerized yagi?
I know there is not a perfect antenna, just wondering about the Helicoil...
Kevin KF7MYK _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Greg, Do not overlook the 2.4 GHz grid dishes. I have successfully added a quad loop for 23 cm (1.2GHz) and have been pleasantly surprised with the performance. I have used one for transmit on 2.4 and receive on 1.2 for ATV work. A single dish with two microwave bands.
Art, KC6UQH
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Greg D. Sent: Monday, July 11, 2011 9:14 PM To: amsat-bb@amsat.org Subject: [amsat-bb] Re: 70cm Helicoil Good/Bad expensive?
I second Jim's assessment here. Helical antennas are the only way I will build an antenna at 1.2 ghz or higher. It's not worth the stress trying to measure things to the precision needed for a Yagi at those frequencies. The less stress (and time) taken to build the antenna, the more enjoyment you will get from actually using it!
For 2m and 70cm, Yagis are good, but also consider making a Quad or a Quagi (a 2 element Quad with more Yagi elements in front). I used a home-built 8 element Quagi from the ARRL Antenna Handbook for several years as a satellite antenna, until I found a crossed Yagi antenna at a Ham Swap for a price I couldn't pass up. Still have the Quagi, just in case.
Greg KO6TH
Date: Tue, 12 Jul 2011 01:38:17 +0000 From: kq6ea@verizon.net To: amsat-bb@amsat.org Subject: [amsat-bb] Re: 70cm Helicoil Good/Bad expensive?
A "Helicoil" is a threaded insert used to repair stripped threads.
I think you're asking about a HELICAL antenna.
They work very well, and are easy to build. They're very forgiving in construction errors, but have a few pitfalls you want to watch out for.
You do NOT want to wind one on PVC pipe for a support, as the dielectric constant of the PVC will throw off the antenna from the design numbers you use to wind the "coil".
This type of helical is called an "Axial Mode" antenna. A "Normal Mode" helical is how a rubber duck is made, and is not what you want.
The ARRL Antenna Handbook has several designs that work well, and there's a TON of information on the Web about building an "Axial Mode Helical Antenna".
They're fixed polarization, determined when you wind it, and the only way to switch between left-hand and right-hand is to have another antenna, and switch to it.
I've built several, and they work pretty well. They get pretty big at 2 Meters, but are manageable (at least for me!) at 70cm and up.
73, Jim KQ6EA
On 07/12/2011 12:39 AM, Kevin Deane wrote:
Hello all, whats the take on these antennas? I am sure someone on here
has used them and they certainly look cool but how do they perform?
Dont you have to switch polerization on a cross polerized yagi?
I know there is not a perfect antenna, just wondering about the
Helicoil...
Kevin KF7MYK _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite
program!
Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
_______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
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Hi Art,
I've got a BBQ Grill too, but used a 3 1/4 turn helix for a feed. I was able to work AO-40 at apogee with it. Definitely a nice system.
How big is your dish? I've not seen a Grill antenna much bigger than the one I currently have, and I'm told it's not big enough for 1.2 ghz (only 30"). Supposed to need at least 4'. So instead I built a helix for that band and did some L/S and L/U through AO-51. Then I found a commercial long boom 1.2 ghz yagi at another Ham Swap (gotta keep me away from those!), and replaced the Helix. But, you know, I don't think the new antenna improved things. Mechanically, yes, but not RF. The Beacon off to the West is about the same on either one.
Given the lack of S-band on the current birds, I was thinking about taking down the Grill for a while, just to lighten the load on the rotor motors. Maybe put up a Wi-Fi flat panel, just to keep the band open. But if I can get both 1.2 and 2.4 out of the Grill instead, might that be better?
Greg KO6TH
From: kc6uqh@cox.net To: ko6th_greg@hotmail.com; amsat-bb@amsat.org Subject: RE: [amsat-bb] Re: 70cm Helicoil Good/Bad expensive? Date: Mon, 11 Jul 2011 21:26:17 -0700
Greg, Do not overlook the 2.4 GHz grid dishes. I have successfully added a quad loop for 23 cm (1.2GHz) and have been pleasantly surprised with the performance. I have used one for transmit on 2.4 and receive on 1.2 for ATV work. A single dish with two microwave bands.
Art, KC6UQH
Maybe he was thinking of one of these.......... http://va6bc.no-ip.com/jerry_pix/Quadrifilar-helix/quadrifilar_helix_antenna... http://www.dxzone.com/dx23282/quadrifilar-helix-antenna.html 73, Harvey K5HV
----- Original Message -----
From: "Greg D." ko6th_greg@hotmail.com To: kc6uqh@cox.net; amsat-bb@amsat.org Sent: Tuesday, July 12, 2011 0:51 AM Subject: [amsat-bb] Re: 70cm Helicoil Good/Bad expensive?
Hi Art,
I've got a BBQ Grill too, but used a 3 1/4 turn helix for a feed. I was able to work AO-40 at apogee with it. Definitely a nice system.
How big is your dish? I've not seen a Grill antenna much bigger than the one I currently have, and I'm told it's not big enough for 1.2 ghz (only 30"). Supposed to need at least 4'. So instead I built a helix for that band and did some L/S and L/U through AO-51. Then I found a commercial long boom 1.2 ghz yagi at another Ham Swap (gotta keep me away from those!), and replaced the Helix. But, you know, I don't think the new antenna improved things. Mechanically, yes, but not RF. The Beacon off to the West is about the same on either one.
Given the lack of S-band on the current birds, I was thinking about taking down the Grill for a while, just to lighten the load on the rotor motors. Maybe put up a Wi-Fi flat panel, just to keep the band open. But if I can get both 1.2 and 2.4 out of the Grill instead, might that be better?
Greg KO6TH
From: kc6uqh@cox.net To: ko6th_greg@hotmail.com; amsat-bb@amsat.org Subject: RE: [amsat-bb] Re: 70cm Helicoil Good/Bad expensive? Date: Mon, 11 Jul 2011 21:26:17 -0700
Greg, Do not overlook the 2.4 GHz grid dishes. I have successfully added a quad loop for 23 cm (1.2GHz) and have been pleasantly surprised with the performance. I have used one for transmit on 2.4 and receive on 1.2 for ATV work. A single dish with two microwave bands.
Art, KC6UQH
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Hello Kevin-I have built a few of these antennas over the years. Mostly for 1.2ghz RHCP tx and 2.4ghz LHCP rx for a dish feed. As mentioned the polarization is fixed. The helix antenna is pretty broad banded. I never built one for 70cm or 2m however I have been tempted. Here it comes....Our next HEO will most certainly have L & S band capability. I can only hope I will last that long. If you want some pics I have many. Yeah they do look cool.
73 Bob W7LRD
Seattle
----- Original Message -----
From: "Kevin Deane" summit496@live.com To: amsat-bb@amsat.org Sent: Monday, July 11, 2011 5:39:25 PM Subject: [amsat-bb] 70cm Helicoil Good/Bad expensive?
Hello all, whats the take on these antennas? I am sure someone on here has used them and they certainly look cool but how do they perform? Dont you have to switch polerization on a cross polerized yagi? I know there is not a perfect antenna, just wondering about the Helicoil...
Kevin KF7MYK _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
participants (7)
-
Art McBride -
Bob- W7LRD -
Greg D. -
H. Vordenbaum -
Jim Jerzycke -
Kevin Deane -
Nigel Gunn G8IFF/W8IFF