Antenna location question

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JEL
Posts: 131
Joined: Wed Feb 07, 2018 2:08 am

Antenna location question

Post by JEL » Wed Sep 11, 2019 10:52 am

In your experience, which is generally better for reception purposes:



For HF and random long-wire antenna:

High placement indoors (2nd floor attic)
vs
Low placement outdoors (garden at 1st floor ground-level)

(Does the same apply if using loop-antenna?)



For VHF and discone antenna:

High placement indoors (2nd floor attic)
vs
Low placement outdoors (garden at 1st floor ground-level)


In my case indoors is in a rebar building (at least I think that's what it's called) with brick walls (I think there is concrete elements in the walls also, behind the brick-layer, but I'm not sure. The roof-tiling is something very heavy and thick also. I can't see what the material is, only that the tiles are orange. Some type of cement or clay I suppose)

The garden is surrounded by large trees (which I can't put any antennas into/onto, unfortunately (they're not mine))

Anyway, I'm looking for some hints on which option I should explore first, in relation to antenna-placement; the ground-level garden outside or the attic inside on the 2nd floor.

Thank you
jacob.

snn47
Posts: 192
Joined: Tue Dec 27, 2016 11:00 pm

Re: Antenna location question

Post by snn47 » Thu Oct 10, 2019 2:15 pm

Since HF covers about 160 m to 10 m of wavelength performance will be dependent on Frequency.

You will receive signals, but unless you bring an antenna into resonance it is impossible to predict antenna pattern in azimuth and elevation.

With loop antenna do you refer to untuned ones or tuned one windiing with <1/4 lambda length as used by HAM OP. I sucessfully used the tuned magnetic loops indoor up to 100W transmitter power. The magnetic loop was optimized for 10 m to 20m range with limitations down to 40 m. A larger magnetic loop did not improve performance indoor for me (3rd floor of 4 + roof, brick walls and other building just 5 m away). The largest benefit during reception was the narrow bandwidth which even allowed operation on 40 m with a not so great receiver which was without the magnetic loop as preselector completely overloaded.


Discones have a bandwidth covering about an oktave or 1:8 frequency range. and you did not specify the frequency range yours covers. From my experience as HAM indoor performance improves if the antenna height is small compared to the height of a room and not placed close to shielding windows e.g. those with metall vapour, walls etc.

Placing antenna higher will increase the Radio Line of Sight and you will most likely receive mor stations/signals unless the receiver is overloaded by to many (strong) stations.

I hope that helps

JEL
Posts: 131
Joined: Wed Feb 07, 2018 2:08 am

Re: Antenna location question

Post by JEL » Sat Oct 12, 2019 12:44 am

Hi SNN47 :)

I have been occupied with non-radio things for a while, so I have not had a lot of time to do further testing of this.

Currently, for HF, I took a 10 meter (30 feet) long wire and drew it from the 1st floor to the 2nd floor.
I have not been able to experiment with its placement much, but I do get some signals on it.

The VHF discone is put on the 2nd floor where there is some spare-room for now and it does receive, but nothing magical.
I get a tad more signals there than when I had it on the 1st floor though (both tests where indoor)
I have only been able to try it outside in the garden for an hour so far, but that did not appear to increase reception vs indoor on the 1st floor any.
On the 2nd floor it pulls in a slight bit more signal ( ~3 dB more )

I hope to be able to do some more thorough experiments with placement at a later time, to see if I can find the sweet-spots that hopefully exist somewhere :)

Unfortunately, for these purposes at least, the building I am in now is very much a Faraday-cage (And ~35 feet lower in ground-elevation vs the previous place. On top of that the floor-elevation of the current 2nd floor is about where my main floor was in the previous place. So reception has gone a bit downhill, pun intended :) ), so I probably won't be able to make much improvement in reception.

Thank you very much for your input :)
jacob.

snn47
Posts: 192
Joined: Tue Dec 27, 2016 11:00 pm

Re: Antenna location question

Post by snn47 » Sat Oct 12, 2019 7:06 pm

30 ft is close to fullwave for 10 m (1/4 lamda is ~2.5 m) so the wire should work down to about 40 m.

However if it is close to your house and it is shielded as you wrote, it will influence reception and resonance.If you have metall tubes (water/heating) you can try to use them as ground and see if this helps.

JEL
Posts: 131
Joined: Wed Feb 07, 2018 2:08 am

Re: Antenna location question

Post by JEL » Sat Oct 12, 2019 9:00 pm

It is still caught inside the house, which was built in the late 70s or early 80s when it was on fashion to hide all plumbing inside the walls and use concrete reinforced with rebar 'grates'. So it's really not a house built for people having radio-reception as a hobby :) (And for some reason putting up an antenna outside is not allowed anymore. Hopefully that fashion will change again one day and the look of an antenna will be perceived as something beautiful. I wouldn't mind, but radio-people are a minority these days)

Later I will try to experiment with a loop and perhaps also with sticking a ground-spear deep into the garden.

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