[HamWAN PSDR] KU7M and his dBm
Dean Gibson AE7Q
hamwan at ae7q.com
Sat May 24 09:03:15 PDT 2014
Kenny, I note that both you and I have the "ledge" of the base of the
antenna to the right. I wonder if whatever is in the plastic "knob" at
the end of the antenna stalk has a little vertical loop or other
non-symmetrical element in it, that alters the takeoff angle? I'm not
about to reorient my antenna on its mast, but if you are interested in
doing it on yours ...
I have previously assumed that my "beam" (which is aimed vertically to
just clear the roof of the nearby house) just strikes enough
leaves/branches/water tower on its path to deflect a portion of the
signal back down so as to reach Paine. I still think that's what it is,
especially after Bart's comment that a clear shot might get me another
20-30dB.
ps: In my previous analysis of the mathematically-correct takeoff angle
for my antenna, I forgot to include the curvature of the earth. In my
case (5 miles to the Paine), it effectively reduces the "rise" by 16.5
feet (about a 5% error in the angle, not a significant factor in the
calculation).
On 2014-05-23 20:17, Kenny Richards wrote:
> Is there anybody else connecting to the sector antennas that Dean and
> I are using? (I know we are connecting to different sites, but to the
> two sector antennas in question?)
>
> Sent from my iPad
>
> On May 23, 2014, at 7:19 PM, Bart Kus <me at bartk.us
> <mailto:me at bartk.us>> wrote:
>
>> Sounds like we need to take a closer look at the vertical radiation
>> pattern. Maybe something is actually going on there.
>>
>> --Bart
>>
>>
>> On 5/23/2014 2:33 PM, Dean Gibson AE7Q wrote:
>>> It may be "super weird", but I'm seeing the same thing. My antenna
>>> is at 450'; the Paine antenna is at 750', and the distance between
>>> the two is almost exactly 26400'. That's a rise of 300' in 26400',
>>> and the arc-sine of that ratio (0.0113636) is .65 degrees. However,
>>> for optimum results, I have my antenna also aimed about 5 degrees
>>> above the horizon. I don't remember the exact results when I aim at
>>> less than one degree, but it's significantly less.
>>>
>>> On 2014-05-22 13:28, Bart Kus wrote:
>>>> That's super weird. You might wanna try moving the mount up/down
>>>> the mast while keeping the dish level. And yes, microwaves can be
>>>> mysterious until you get experience with them. That's one big
>>>> advantage of doing a project like this, it gives hams motivation to
>>>> learn how to deal with 6GHz and such.
>>>>
>>>> --Bart
>>>>
>>>>
>>>> On 5/22/2014 1:03 PM, Kenny Richards wrote:
>>>>> Bart,
>>>>>
>>>>> >Would you like some tower climbing / install help? That's some crazy uptilt on
>>>>> the antenna picture you showed!
>>>>>
>>>>> Thank you for the offer, but I think it can wait until I'm healed.
>>>>> This was 'minor' knee surgery and I should be back to working out
>>>>> in six weeks, so I'm sure climbing the tower will be doable by
>>>>> then. We are at the very beginning of tower climbing season....
>>>>>
>>>>> The crazy uptilt required was the source of most of my headaches.
>>>>> From that exact location, I will hear nothing with the antenna at
>>>>> the normal 'level' mount point. You need to tilt it up about five
>>>>> degrees or more before CP will register. It never occurred to me
>>>>> that it would have that big of impact. Microwaves are weird....
>>>>>
>>>>> Thanks
>>>>> Kenny
>>>>>
>>>>>
>>>>>
>>>>> On Wed, May 21, 2014 at 11:54 PM, Bart Kus <me at bartk.us
>>>>> <mailto:me at bartk.us>> wrote:
>>>>>
>>>>> Dean,
>>>>>
>>>>> I wouldn't limit your potential upside to 3dB with ...
>>>>> "spatial modulation". :) The vast majority of your path loss
>>>>> is NOT due to distance. If you did achieve clear (or better)
>>>>> LoS, you could be looking at 30dB deltas. Remember we've had
>>>>> Baldi-Tacoma (a far longer distance than yours) run at -57dBm
>>>>> during a signal survey. K7JMM, across the Puget Sound (about
>>>>> 3x your distance) is running at -58dBm right now.
>>>>>
>>>>> Kenny,
>>>>>
>>>>> Would you like some tower climbing / install help? That's
>>>>> some crazy uptilt on the antenna picture you showed!
>>>>>
>>>>> --Bart
>>>>>
>>>>>
>>>>>
>>>>> On 5/21/2014 9:27 PM, Kenny Richards wrote:
>>>>>> Dean,
>>>>>>
>>>>>> I'm slightly less mad at you, but still a little peeved. :-)
>>>>>>
>>>>>> The shot to Capital Park from my house goes through quite a
>>>>>> few tree's in my immediate area. (All within a couple blocks
>>>>>> from me) When I originally installed the tower about 10
>>>>>> years ago, I was able to see downtown from the top of it. Now
>>>>>> I can't, due to the trees of the neighbor directly behind me
>>>>>> and his neighbor.
>>>>>>
>>>>>> That said, I don't actually have the HamWAN antenna mounted
>>>>>> on the tower yet. I had to postpone that installation until
>>>>>> my knee heals up. (Had the meniscus repaired in my left knee
>>>>>> last week) Right now the antenna is mounted to a small mast
>>>>>> at the apex of the roof. (It is sharing the mast with a
>>>>>> VHF/UHF vertical)
>>>>>>
>>>>>> I thought that I'd posted links to these pictures before, but
>>>>>> I guess not.
>>>>>>
>>>>>> Picture of current installation:
>>>>>> http://www.ku7m.net/drop/KU7M_HamWAN.JPG
>>>>>>
>>>>>> Picture of what I'm shooting through to get to Capital Park:
>>>>>> http://www.ku7m.net/drop/KU7M_CPView.JPG
>>>>>>
>>>>>> And just because it makes me laugh, the installation from the
>>>>>> first night it started working:
>>>>>> http://www.ku7m.net/drop/DeckAntennaMount.jpg
>>>>>>
>>>>>> The difference in signal strength from the antenna being on
>>>>>> the deck railing to its current location is ~5 dB. The height
>>>>>> difference between the to location is about eight to ten
>>>>>> feet. When moving the antenna to the roof the first time, I
>>>>>> had originally installed it on a mast located at the far east
>>>>>> side of the roof. In this spot I could not hear CP at all. By
>>>>>> moving the antenna to the mast located in the center of the
>>>>>> house (which is about 20-25 feet west), the signal appeared
>>>>>> and has so far been the best location. I ordered another
>>>>>> mast mounting kit for the eve located at the far west side of
>>>>>> the house. When I'm feeling better I'll install it and see if
>>>>>> the signal improves again when moving west.
>>>>>>
>>>>>> I don't have many data points on the impact of wind on the
>>>>>> signal strength. I did check it on Sunday when a system blew
>>>>>> through which was causing the trees to noticeable move. But I
>>>>>> wasn't seeing much change in the signal strength. (maybe 1 db?)
>>>>>>
>>>>>> Thanks
>>>>>> Kenny
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Wed, May 21, 2014 at 7:44 PM, Dean Gibson AE7Q
>>>>>> <hamwan at ae7q.com <mailto:hamwan at ae7q.com>> wrote:
>>>>>>
>>>>>> First of all, Kenny: welcome! Now that you have a
>>>>>> HamWAN connection, I hope you are no longer mad at me.
>>>>>> Where is your antenna (inside/outside, height above
>>>>>> ground, etc)?
>>>>>>
>>>>>> On a related but more serious side, do you have a direct
>>>>>> line-of-sight path to Capitol Hill, or do you go through
>>>>>> trees? The reason I ask is, my path goes through some
>>>>>> trees. When it is windy, that causes my RX signal level
>>>>>> (dBm value) to vary about 5 dB (mostly down). I have
>>>>>> wondered whether mounting my antenna higher would help my
>>>>>> overall value (of course it would help when it is windy).
>>>>>>
>>>>>> My average RX signal level is 80 dBm (no winds), and
>>>>>> yours appears to be 83 dBm. However, you are twice as
>>>>>> far from your cell site as I am from mine, and since
>>>>>> power falls off as the square of the distance, I'd expect
>>>>>> (in similar configurations and siting) that you would
>>>>>> experience a 6 dB difference. Since the difference is
>>>>>> only 3 dB, that suggests that (all things being equal,
>>>>>> which they never are) I might gain *at most* 3 dB by
>>>>>> moving the antenna.
>>>>>>
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>>>>>>
>>>>>>
>>>>>>
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