[VHFcontesting] Portable 50 MHz beam antennas

[Mark Spencer]

Hi Bill.   Good point re the height issue.   Yes I am planning on taking an approx 20 mast with me during my back packing trips.   I've found while roving from my truck that getting the 50 MHz beam at least a wave length over ground helps quite a bit.

I took a look at one of my roving masts and figure it is just barely viable for back pack outings.   (I'm aiming for a total load of 50 pounds including radio, battery, mast and antenna.)  I hope I'm still up to hauling a 50 pound pack around (:  My first planned outing is going to be a fairly easy walk up a de activated logging road that I don't want to drive my truck up.

73

Mark S
VE7AFZ

Aligned Solutions Co.
mark at alignedsolutions.com
604 762 4099

> On Feb 16, 2018, at 9:07 AM, Bill Olson <callbill at hotmail.com> wrote:
> 
> Hi all, This might be a good time to bring up "height above average terrain" for a 6 meter beam. I'll digress here a little then will get back to the point. I used to rove with the lower 6 bands. Antennas were all mounted on a rotor fixed to roof racks on my truck. There were ~ 8 ft yagis and loop Yagis on 2 thru 1296 BUT on 6 meters I had an old 4 element Yagi on a 12 foot boom. This got mounted right above the rotor so was maybe 7 feet off the ground. (Yeah the ~9-10ft long 6M elements hung over the sides of the vehicle a little - never was a problem with law enforcement hi). Everything worked great except 6M. It had reasonable SWR and I knew the Yagi worked because I had used it on the tower.. but signals were weak except when the band opened for e-skip.. Well that should have tipped me off right there but It wasn't until I had a talk with Pete, K9PW, who used to operate with the AA9D multi-multi VHF contest station in central Illinois. They had done some experiments with 
> their rovers and found that just a HALO antenna at 25 feet WAY out performed a multi-element Yagi at 10 feet.. Well duh, of course the Yagi's pattern in the vertical plane got more and more elevated off the horizon the closer it got to the ground and at 10 feet there was practically no response on the horizon. I haven't done any of the math BUT just experimenting with it, I arrived at about 20 feet for my rover 6M antenna. I built a 2 element beam on a four foot boom. This could easily ride on the roof racks  with the elements pointing fore and aft. I put together a 20 foot mast and that got stowed up there too.. So, yeah, no operating 6m while in motion, but with a trailer hitch sort of mount for the mast, it really only took a couple minutes to get the 6M beam in place.. Armstrong rotated for me, but here in Maine pretty much everyone is in the same direction and with abroad pattern it was pretty much set it and forget it.. The results were quite amazing and all of a sudde
> n I worked stations on tropo at several hundred miles..
> 
> 
> To get back to the back-packer antennas, folding up the antenna and making it "packable" is one thing but then you need a 20 foot mast too and a way to keep it up in those high mountaintop winds!! The gain of the antenna is not doing you any good if it's peak is above the horizon and there is a null AT the horizon!
> 
> 
> just saying..
> 
> 
> bill, k1DY in Maine
> 
> 
> ________________________________
> From: VHFcontesting <vhfcontesting-bounces at contesting.com> on behalf of Mark Spencer <mark at alignedsolutions.com>
> Sent: Thursday, February 15, 2018 4:22 PM
> To: Bob K0NR - email list
> Cc: vhfcontesting at contesting.com
> Subject: Re: [VHFcontesting] Portable 50 MHz beam antennas
> 
> Thanks All.  I got some great on and off list responses.
> 
> Yes I believe the 40" length limit is a reasonable one.   (I have found carrying 48" mast sections via backpack to be a bit awkward for me.)
> 
> 73
> 
> Mark S
> VE7AFZ
> 
> Aligned Solutions Co.
> mark at alignedsolutions.com
> 604 762 4099
> 
>> On Feb 15, 2018, at 7:17 AM, Bob K0NR - email list <list at k0nr.com> wrote:
>> 
>> Zack,
>> 
>> I'd be interested in the 144 MHz yagi design for backpack portable operating.
>> Its got to be compact and easy to assemble, otherwise it tends to get left at home.
>