Mike,
Tom, W8JI has a comparison between 1/4 wave and 5/8 wave vertical mobile
antennas here: http://www.w8ji.com/VHF%20mobile%20vertical.htm
He is comparing mobile antennas but it looks like the 5/8 wave can be 2 db
better than the 1/4 wave.
Looking at the radiation angle graphs it shows the 5/8 has more gain at lower
radiation angles in particular.
If you were doing your comparison on long haul contacts it makes sense that the
5/8 would do better.
Bob
K6UJ
On Sep 6, 2013, at 4:35 PM, Mike Armstrong wrote:
> Guy, you aren't reading my emails...... because that question is not
> appropriate to the conversation. I am NOT, I repeat NOT talking the
> difference between LOCATIONS, but the difference between ANTENNAS AT THE SAME
> LOCATION! I am NOT talking about RURAL ANYTHING. That location being on
> Gannet Avenue across from the Marina that was LITERALLY across the street
> from my house.
>
> I say again, READ MY EMAIL as your question has absolutely NOTHING to do with
> the conversation. The fact that you sent the same email to me after I
> answered you tells me that you are not reading what I wrote. I am not being
> insulting, but if you don't read ALL of what I wrote, you cannot possibly ask
> a valid question or make any statements about its content. If you read it,
> you would know that I am not saying ANYTHING about location changes or
> differences. OF COURSE a sea water location is better than a rural location.
> THAT fact has nothing to do with the comparisons I am making or asking Tom
> to discuss. Sorry for the repetition, but I want to make sure that you will
> see that, even if you don't read this email entirely. Again, no insult
> intended, but it is tiring trying to respond to someone who isn't reading ALL
> of what I wrote and jumping to incorrect conclusions as a result. I WILL
> tell you the address, if you still want to know, after you have read and
> responded
to
> the content of this email specifically.
>
> Mike AB7ZU
>
> Kuhi no ka lima, hele no ka maka
>
> On Sep 6, 2013, at 13:38, Guy Olinger K2AV <olinger@bellsouth.net> wrote:
>
>> Mike, could you kindly supply the address on Iroquois Point? If it's in
>> the area I'm looking at with Google Earth, the answer why the difference is
>> pretty plain, and points to why such a difference vs. a 160m vertical on
>> rural terra firma.
>>
>> 73, Guy.
>>
>>
>> On Fri, Sep 6, 2013 at 1:30 PM, Mike Armstrong <armstrmj@aol.com> wrote:
>>
>>> Oh, I didn't address one comment you made, Tom...... 5/8ths are dogs on
>>> 160? Really? That is odd in the extreme to me. I had incredible success
>>> with a ground mounted 5/8 on 20 meters while I was stationed in Hawaii. I
>>> was rather space limited, so I could only go up and a tower mounted beam
>>> was a "no fly zone" in that particular situation. So, I decided to try the
>>> 5/8ths wave vertical and its performance was nothing short of spectacular
>>> when compared to a 1/4 under the same circumstances. Not to malign the
>>> simple 1/4 wave, but the 5/8ths performance improvement went way beyond
>>> what I would have expected...... and my expectations were certainly
>>> reasonable. My thinking was that lifting the major current node a bit
>>> above ground would probably be an improvement and, to my surprise, that was
>>> an understatement in the extreme.
>>>
>>> I wouldn't want to overblow the results, but I simply couldn't believe how
>>> well the antenna performed on 20. To be sure, I was on Oahu out in
>>> Iroquois Point housing, which is well situated with regard to the sea (you
>>> are basically ON the water in almost all directions). Additionally, I had
>>> 60 radials underneath the thing, spread evenly around the base (in straight
>>> lines, no bending). So it was definitely an ideal vertical location. But
>>> the difference between it and the quarter wave was what truly surprised me
>>> (with all else being the same.... sea water location, number and length of
>>> radials, etc). To hear that it doesn't translate to 160 is really a
>>> surprise to me...... Tell me more, assuming you did any kind of study into
>>> why it didn't seem to work well. I am as interested in why something
>>> DIDN'T work as I am in why it does..... If for no other reason than to save
>>> a few bucks and alot of time.... LOL
>>>
>>> Mike AB7ZU
>>>
>>> Kuhi no ka lima, hele no ka maka
>>>
>>> On Sep 6, 2013, at 9:25, "Tom W8JI" <w8ji@w8ji.com> wrote:
>>>
>>>>> Fully understood. I wasn't referring to the usual collinear antennas
>>> sold by "comet" or anything of that nature. I am referring to the stacking
>>> arrangements used for ops like moonbounce, etc. As far as the design
>>> theory (and practical application) goes, I have a reasonable amount of
>>> schooling and experience (been active since 1966..... he he he). Just so
>>> you realize I am not referring to the often (always?) false gain claims
>>> made by manufacturers for their antenna designs.
>>>>
>>>> ........but this is verticals, and not a narrow BW like a long Yagi. The
>>> narrower the pattern of a cell in the stack, the wider minimum useful
>>> stacking distance becomes.
>>>>
>>>> Also, for 160, antennas are near earth. Earth spoils everything. A 160
>>> antenna at 260 feet is like a two meter antenna at 3.25 feet above ground.
>>>>
>>>>
>>>>> All I was saying was, "yes, it is possible and is done" when speaking
>>> to vertical stacking. As far as stacking what we would call "ground plane"
>>> antennas (quarter wave vertical element against elevated radials), the only
>>> example I have seen with any regularity is done aboard some Naval vessels
>>> (stacked/phased, if you will, horizontally on a yard arm). I "think" I have
>>> seen the same thing at airports, but I cannot tell for certain that they
>>> are phased arrays or just happen to "look" like they are related.
>>> Understand that in all cases to which I refer, including my own, I am
>>> speaking of phased arrays, which I believe is what we are talking about as
>>> well. I may have misinterpreted the question to some degree.
>>>>
>>>> This is 160. The distance ratio for the same behavior on two meters is
>>> 80:1. If we look at: http://www.w8ji.com/stacking_broadside_collinear.htm
>>>>
>>>> we see **freespace** short dipole stacking distances, between current
>>> maximums, is 0.35 WL for 1 dB stacking gain. This is for freespace. That
>>> means the current maximums have to be .35*160 = 56 meters apart **if** the
>>> elements are in freespace. They have to be even further apart if near
>>> earth, because the earth reflection already compresses the vertical
>>> pattern. I'd guess, for 1 dB stacking gain over a ground mounted vertical
>>> (ignoring ground losses), we could move the lower current maximum to about
>>> 50 meters above earth and eliminate the upper element. That would pretty
>>> much be a vertical dipole. If we wanted to get 2-3 dB gain, we'd probably
>>> need 300 feet of height and an inverted groundplane at the top.
>>>>
>>>> For 160, is it is a useless endeavor at normal heights.
>>>>
>>>> Making matters worse, 5/8th wave verticals are dogs on 160. Been there,
>>> done that, used them. A 1/4 wave vertical, or something up to maybe 200
>>> feet, is actually better. They have never worked well here, they never
>>> worked when I used broadcast towers, and when W8LT used them in 160
>>> contests they were also pretty weak.
>>>>
>>>> The whole thing is a waste of time on 160. Even if someone could run a
>>> vertical collinear with useful gain, it would just kill their signal by
>>> focusing it at too low an angle for 160, while nulling more useful angles.
>>>>
>>>> 73 Tom
>>> _________________
>>> Topband Reflector
>> _________________
>> Topband Reflector
> _________________
> Topband Reflector
_________________
Topband Reflector
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