I was fooling around with a 7dbi antenna. Attached a coax for use outside.
I don't exactly how these wireless units operate, but was thinking about
ground planes. I used a simple rf pickup device watching 10 hz pulses from
unit. As I moved from top of antenna I went through nodes, but continued to
get nodes on coax down a ways. I set the rf monitor out from antenna, and
installed ferrite core around coax about 1/4 wavelength from connector. I
think it improved overall radiation, and the rf did not go beyond the core.
What you think?
On 12/15/2011 1:48 PM, gregz wrote:
> I was fooling around with a 7dbi antenna. Attached a coax for use outside.
> I don't exactly how these wireless units operate, but was thinking about
> ground planes. I used a simple rf pickup device watching 10 hz pulses from
> unit. As I moved from top of antenna I went through nodes, but continued to
> get nodes on coax down a ways. I set the rf monitor out from antenna, and
> installed ferrite core around coax about 1/4 wavelength from connector. I
> think it improved overall radiation, and the rf did not go beyond the core.
> What you think?
>
> Greg
Near field measurements are tricky. I'm not sure I'd trust them.
For RF, generally you coil up the coax like an inductor, and it makes a
common mode choke. That takes the ferrite performance out of the equation.
There are some really high frequency ferrites these days. You can get
3GHz transformers if you want total electrical isolation. Coiled coax
would be less loss though.
miso <miso@sushi.com> wrote:
> On 12/15/2011 1:48 PM, gregz wrote:
>> I was fooling around with a 7dbi antenna. Attached a coax for use outside.
>> I don't exactly how these wireless units operate, but was thinking about
>> ground planes. I used a simple rf pickup device watching 10 hz pulses from
>> unit. As I moved from top of antenna I went through nodes, but continued to
>> get nodes on coax down a ways. I set the rf monitor out from antenna, and
>> installed ferrite core around coax about 1/4 wavelength from connector. I
>> think it improved overall radiation, and the rf did not go beyond the core.
>> What you think?
>>
>> Greg
>
> Near field measurements are tricky. I'm not sure I'd trust them.
>
> For RF, generally you coil up the coax like an inductor, and it makes a
> common mode choke. That takes the ferrite performance out of the equation.
>
> There are some really high frequency ferrites these days. You can get
> 3GHz transformers if you want total electrical isolation. Coiled coax
> would be less loss though.
I'm using a 5 foot piece of coax about the size of rg58. Not much to work
with.
From what I can tell, these antennas do require either a ground plane, or a
tube running over the coax to the connection a quarter wavelength.
I plan on placing the antenna on the outside of an aluminum screen, mounted
in a toilet paper dispenser, horizontally polarized to help interference,
sitting on the window ledge, about a quarter wavelength away from the
screen. I was looking in Kmart for suction cups or something, and noticed
the dispenser. Drilled out the ends, stuck antenna through.
>
> I'm using a 5 foot piece of coax about the size of rg58. Not much to work
> with.
> From what I can tell, these antennas do require either a ground plane, or a
> tube running over the coax to the connection a quarter wavelength.
>
> I plan on placing the antenna on the outside of an aluminum screen, mounted
> in a toilet paper dispenser, horizontally polarized to help interference,
> sitting on the window ledge, about a quarter wavelength away from the
> screen. I was looking in Kmart for suction cups or something, and noticed
> the dispenser. Drilled out the ends, stuck antenna through.
>
> Greg
It sounds like you are making a reflector and not a ground plane.
miso <miso@sushi.com> wrote:
>>
>> I'm using a 5 foot piece of coax about the size of rg58. Not much to work
>> with.
>> From what I can tell, these antennas do require either a ground plane, or a
>> tube running over the coax to the connection a quarter wavelength.
>>
>> I plan on placing the antenna on the outside of an aluminum screen, mounted
>> in a toilet paper dispenser, horizontally polarized to help interference,
>> sitting on the window ledge, about a quarter wavelength away from the
>> screen. I was looking in Kmart for suction cups or something, and noticed
>> the dispenser. Drilled out the ends, stuck antenna through.
>>
>> Greg
>
> It sounds like you are making a reflector and not a ground plane.
On 12/17/2011 7:59 PM, gregz wrote:
> miso<miso@sushi.com> wrote:
>>>
>>> I'm using a 5 foot piece of coax about the size of rg58. Not much to work
>>> with.
>>> From what I can tell, these antennas do require either a ground plane, or a
>>> tube running over the coax to the connection a quarter wavelength.
>>>
>>> I plan on placing the antenna on the outside of an aluminum screen, mounted
>>> in a toilet paper dispenser, horizontally polarized to help interference,
>>> sitting on the window ledge, about a quarter wavelength away from the
>>> screen. I was looking in Kmart for suction cups or something, and noticed
>>> the dispenser. Drilled out the ends, stuck antenna through.
>>>
>>> Greg
>>
>> It sounds like you are making a reflector and not a ground plane.
>
> There is a reflector involved.
>
> Greg
Have you considered building the biquad? It can easily be swapped from
horizontal to vertical polarization. Taking a tip from Jeff, I built one
using round loops rather than square. Just keep the circumference the same.
My point is you would probably get better results using a known design
with a bit of science behind it rather than just hacking.
miso <miso@sushi.com> wrote:
> On 12/17/2011 7:59 PM, gregz wrote:
>> miso<miso@sushi.com> wrote:
>>>>
>>>> I'm using a 5 foot piece of coax about the size of rg58. Not much to work
>>>> with.
>>>> From what I can tell, these antennas do require either a ground plane, or a
>>>> tube running over the coax to the connection a quarter wavelength.
>>>>
>>>> I plan on placing the antenna on the outside of an aluminum screen, mounted
>>>> in a toilet paper dispenser, horizontally polarized to help interference,
>>>> sitting on the window ledge, about a quarter wavelength away from the
>>>> screen. I was looking in Kmart for suction cups or something, and noticed
>>>> the dispenser. Drilled out the ends, stuck antenna through.
>>>>
>>>> Greg
>>>
>>> It sounds like you are making a reflector and not a ground plane.
>>
>> There is a reflector involved.
>>
>> Greg
>
> Have you considered building the biquad? It can easily be swapped from
> horizontal to vertical polarization. Taking a tip from Jeff, I built one
> using round loops rather than square. Just keep the circumference the same.
>
> My point is you would probably get better results using a known design
> with a bit of science behind it rather than just hacking.
>
>> http://martybugs.net/wireless/biquad/
>
> I built one very similar to the Marty design. Instead of messing with the
> pipe, I hacked an old N connector. Something like this would work:
>> http://www.frys.com/product/2924495?...H:MAIN_RSLT_PG
>
> Of course when push came to shove, I just bought a high gain antenna. But
> the hacked antenna was interesting, just to see what I could make.
I have looked at all designs. The project is currently in hold since I
found another approach. I would like to try and make the biquad sometime.
miso <miso@sushi.com> wrote:
> On 12/17/2011 7:59 PM, gregz wrote:
>> miso<miso@sushi.com> wrote:
>>>>
>>>> I'm using a 5 foot piece of coax about the size of rg58. Not much to work
>>>> with.
>>>> From what I can tell, these antennas do require either a ground plane, or a
>>>> tube running over the coax to the connection a quarter wavelength.
>>>>
>>>> I plan on placing the antenna on the outside of an aluminum screen, mounted
>>>> in a toilet paper dispenser, horizontally polarized to help interference,
>>>> sitting on the window ledge, about a quarter wavelength away from the
>>>> screen. I was looking in Kmart for suction cups or something, and noticed
>>>> the dispenser. Drilled out the ends, stuck antenna through.
>>>>
>>>> Greg
>>>
>>> It sounds like you are making a reflector and not a ground plane.
>>
>> There is a reflector involved.
>>
>> Greg
>
> Have you considered building the biquad? It can easily be swapped from
> horizontal to vertical polarization. Taking a tip from Jeff, I built one
> using round loops rather than square. Just keep the circumference the same.
>
> My point is you would probably get better results using a known design
> with a bit of science behind it rather than just hacking.
>
>> http://martybugs.net/wireless/biquad/
>
> I built one very similar to the Marty design. Instead of messing with the
> pipe, I hacked an old N connector. Something like this would work:
>> http://www.frys.com/product/2924495?...H:MAIN_RSLT_PG
>
> Of course when push came to shove, I just bought a high gain antenna. But
> the hacked antenna was interesting, just to see what I could make.
Was that n a good one, like brass underneath, solderable?
On 12/19/2011 12:53 PM, gregz wrote:
> miso<miso@sushi.com> wrote:
>> On 12/17/2011 7:59 PM, gregz wrote:
>>> miso<miso@sushi.com> wrote:
>>>>>
>>>>> I'm using a 5 foot piece of coax about the size of rg58. Not much to work
>>>>> with.
>>>>> From what I can tell, these antennas do require either a ground plane, or a
>>>>> tube running over the coax to the connection a quarter wavelength.
>>>>>
>>>>> I plan on placing the antenna on the outside of an aluminum screen, mounted
>>>>> in a toilet paper dispenser, horizontally polarized to help interference,
>>>>> sitting on the window ledge, about a quarter wavelength away from the
>>>>> screen. I was looking in Kmart for suction cups or something, and noticed
>>>>> the dispenser. Drilled out the ends, stuck antenna through.
>>>>>
>>>>> Greg
>>>>
>>>> It sounds like you are making a reflector and not a ground plane.
>>>
>>> There is a reflector involved.
>>>
>>> Greg
>>
>> Have you considered building the biquad? It can easily be swapped from
>> horizontal to vertical polarization. Taking a tip from Jeff, I built one
>> using round loops rather than square. Just keep the circumference the same.
>>
>> My point is you would probably get better results using a known design
>> with a bit of science behind it rather than just hacking.
>>
>>> http://martybugs.net/wireless/biquad/
>>
>> I built one very similar to the Marty design. Instead of messing with the
>> pipe, I hacked an old N connector. Something like this would work:
>>> http://www.frys.com/product/2924495?...H:MAIN_RSLT_PG
>>
>> Of course when push came to shove, I just bought a high gain antenna. But
>> the hacked antenna was interesting, just to see what I could make.
>
> Was that n a good one, like brass underneath, solderable?
>
>
> Greg
Actually it was difficult to solder to the hack-sawed N connector. I
used a small propane torch. You need to be careful not to melt the
insulation in the N-connector. Maybe the pipe is a better idea if you
have some pipe laying around. I doubt you could buy a foot of copper
pipe, so you need to be able to transport the pipe, which is usually in
10ft sections. And you need a pipe cutter.
That's the problem with homebrew stuff. You need the tools.
I used the biquad wispying (like war driving, but with video) in Vegas.
The biquad is pretty good for a little antenna. However the L-com panel
antennas are relatively cheap and decent quality.
I trolled the net looking at reviews from WISP installers. They dissed
quite a few antennas for leaking. L-Com was considered the best of
cheaper products.
Hey, nobody was ever fired for buying Ubiquiti. Occasionally their gear
shows up on ebay at reasonable prices. But for my money, a $40 L-Com
panel goes a long way.
miso <miso@sushi.com> wrote:
> On 12/17/2011 7:59 PM, gregz wrote:
>> miso<miso@sushi.com> wrote:
>>>>
>>>> I'm using a 5 foot piece of coax about the size of rg58. Not much to work
>>>> with.
>>>> From what I can tell, these antennas do require either a ground plane, or a
>>>> tube running over the coax to the connection a quarter wavelength.
>>>>
>>>> I plan on placing the antenna on the outside of an aluminum screen, mounted
>>>> in a toilet paper dispenser, horizontally polarized to help interference,
>>>> sitting on the window ledge, about a quarter wavelength away from the
>>>> screen. I was looking in Kmart for suction cups or something, and noticed
>>>> the dispenser. Drilled out the ends, stuck antenna through.
>>>>
>>>> Greg
>>>
>>> It sounds like you are making a reflector and not a ground plane.
>>
>> There is a reflector involved.
>>
>> Greg
>
> Have you considered building the biquad? It can easily be swapped from
> horizontal to vertical polarization. Taking a tip from Jeff, I built one
> using round loops rather than square. Just keep the circumference the same.
>
> My point is you would probably get better results using a known design
> with a bit of science behind it rather than just hacking.
>
>> http://martybugs.net/wireless/biquad/
>
> I built one very similar to the Marty design. Instead of messing with the
> pipe, I hacked an old N connector. Something like this would work:
>> http://www.frys.com/product/2924495?...H:MAIN_RSLT_PG
>
> Of course when push came to shove, I just bought a high gain antenna. But
> the hacked antenna was interesting, just to see what I could make.
Looking at Martys page, I was wondering if I was getting ripped on rubber
duckies.
Claiming 7 dbi. No, I took one apart. There is multiple sections and a
coil. So with some reflection I should get reasonable gain after all. I
would have to use a screen on the biquad to remain more invisible. I had
access to Copper screen, but not now.
>
> Looking at Martys page, I was wondering if I was getting ripped on rubber
> duckies.
> Claiming 7 dbi. No, I took one apart. There is multiple sections and a
> coil. So with some reflection I should get reasonable gain after all. I
> would have to use a screen on the biquad to remain more invisible. I had
> access to Copper screen, but not now.
>
> Greg
I'm dubious about some of these little duckies claiming 5dbi or 7dbi.
You can't fight physics.
A reflector at the wrong distance can actually be worse. If you really
want to add a reflector to a duckie, I'd look up corner reflector antenna.
Actually I'm drawing a blank here. You want what looks like a corner
reflector, but it is on a ground plane. It looks like a V with the
bottom solid. The corner reflector is just a plane V and usually used
with dipoles.
>
> Looking at Martys page, I was wondering if I was getting ripped on rubber
> duckies.
> Claiming 7 dbi. No, I took one apart. There is multiple sections and a
> coil. So with some reflection I should get reasonable gain after all. I
> would have to use a screen on the biquad to remain more invisible. I had
> access to Copper screen, but not now.
>
> Greg
I'm dubious about some of these little duckies claiming 5dbi or 7dbi.
You can't fight physics.
A reflector at the wrong distance can actually be worse. If you really
want to add a reflector to a duckie, I'd look up corner reflector antenna.
Actually I'm drawing a blank here. You want what looks like a corner
reflector, but it is on a ground plane. It looks like a V with the
bottom solid. The corner reflector is just a plane V and usually used
with dipoles.
miso <miso@sushi.com> wrote:
>>
>> Looking at Martys page, I was wondering if I was getting ripped on rubber
>> duckies.
>> Claiming 7 dbi. No, I took one apart. There is multiple sections and a
>> coil. So with some reflection I should get reasonable gain after all. I
>> would have to use a screen on the biquad to remain more invisible. I had
>> access to Copper screen, but not now.
>>
>> Greg
>
> I'm dubious about some of these little duckies claiming 5dbi or 7dbi. You
> can't fight physics.
>
> A reflector at the wrong distance can actually be worse. If you really
> want to add a reflector to a duckie, I'd look up corner reflector antenna.
>
> Actually I'm drawing a blank here. You want what looks like a corner
> reflector, but it is on a ground plane. It looks like a V with the bottom
> solid. The corner reflector is just a plane V and usually used with dipoles.
I can see the ground plane helping.
It would probably make the curved cardboard/foil reflector work with a
bottom plate.
I didn't tell I was also fooling with it. Hard to test antennas around
reflections.
I'm not going further yet. My preliminary test with flat reflector looked
good in the near field. One inch spacing seemed optimal.
I'm ordering another linksys router. I want to get that repeating a
repeater working.
antenna 
Linear Mode
