[HamWAN PSDR] KU7M and his dBm

Bart Kus me at bartk.us
Fri May 23 19:19:06 PDT 2014 

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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>>>
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