[HamWAN PSDR] KU7M and his dBm
Dean Gibson AE7Q
hamwan at ae7q.com
Fri May 23 14:33:42 PDT 2014
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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>>
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