tg are you on msn
"tg" wrote in message
...

"Greg" wrote in message
...
The main thing is if there was a broadband antenna for the frequency
of interest, the losses in the cable, even a few feet could kill a
signal above 1G .

but isn't that why we have active antennas? to overcome the losses?
also your comments contradict these antennas:
http://www.wimo.de/wifi-omnidirectio...ntennas_e.html
and they're supplied with cables that go up to 8 meters.


Sure, I use 30meter H-1000 cable at 1.4-2.8GHz, you just need adequate
amplification, most cable types have diagrams showing the attenuation
at certain test frequencies.
http://www.elfaelektronika.lt/cgi-bi...914-25&lng=eng
For instance.... there's more types of cable to compare with, but
personally
I like the Belden H-1000, double-shielded with copper braid and foil,
all for a reasonable cost....
You simply just don't use 100m RG174 at GHz frequencies :-)

what type of antenna are you using for 2.8GHz?

"tg" skrev i en meddelelse
...

both if that's at all possible Brian...
I have noticed that upper spectrum antennas tend to be more narrow in
the frequencies they target, unlike lower spectrum discones which try
to cover a wide range. So I'm none the wiser at this stage.

If you want to learn about satellites signals and antennas for it, you
should visit www.uhf-sat.com
In the chatroom im sure you can finde someone to answer all your satellite
questions.

Regards
Brian

"john" wrote in message
...
tg are you on msn

yeah. send yoiur msn contact details to if you
want to hook up.

Above 2.5'ish I've only used it on the spectrum analyzer for stuff
like short range data transmission modules.

Below that, at 2.1-2.2 there are alot of deep space satellites
(it's a 'sport' trying to receive a carrier of far away signals).
ULNA Ultra Low Noise Amplifiers is required directly at the feed.
0.5dBF
Dish and feedhorn is the way to do this.

At 1.7GHz I've used it for reception of Meteosat pictures
(got some on my old site www.gravitywell.org , for instance
http://www.gravitywell.org/meteosat/...globe_vis2.jpg )
Wide FM, 30-40kHz bandwidth required.
Dish and feedhorn was the way for me... 180cm dish.
Picture at http://www.gravitywell.org/station/station.htm
Regular line-amplifiers for sat.tv worked so so but I'd
recommend an 1.0dBF LNA at least... )

At 1.5 there was Inmarsat telephone calls, where I also used a dish :-)
but here I used a broadband helical feed at the focalpoint as the
transmissions are over such a wide spectrum, dish was a 'small' 150cm
I do belive yagis are starting to get usuable around here...
Picture at http://www.gravitywell.org/station/station.htm

At 1.42 - where I use it today - I use an 0.2dBF ULNA on my
3 meter dish with dual probe feedhorn http://www.gravitywell.org/station/dish.jpg .
Officially I use it for hydrogen line amateur radio astronomy.
In-officially I use it for seti - people look at you so weird if you say this hihi :-)

Perhaps you'll find the block schematic setup interesting,
http://www.gravitywell.org/station/block.png

Every band use require a different feedhorn, not just the probe length
but also the tube length and diameter (usually)....
....there is no ultimate 1-3GHz broadband directional antenna.... sorry...


The main thing is if there was a broadband antenna for the frequency
of interest, the losses in the cable, even a few feet could kill a
signal above 1G .

but isn't that why we have active antennas? to overcome the losses?
also your comments contradict these antennas:
http://www.wimo.de/wifi-omnidirectio...ntennas_e.html
and they're supplied with cables that go up to 8 meters.


Sure, I use 30meter H-1000 cable at 1.4-2.8GHz, you just need adequate
amplification, most cable types have diagrams showing the attenuation
at certain test frequencies.
http://www.elfaelektronika.lt/cgi-bi...914-25&lng=eng
For instance.... there's more types of cable to compare with, but personally
I like the Belden H-1000, double-shielded with copper braid and foil,
all for a reasonable cost....
You simply just don't use 100m RG174 at GHz frequencies :-)

what type of antenna are you using for 2.8GHz?

"Brian Kals" wrote in message
k...

If you want to learn about satellites signals and antennas for it,
you should visit www.uhf-sat.com

'The page cannot be displayed'

"tg" skrev i en meddelelse
...

"Brian Kals" wrote in message
k...

If you want to learn about satellites signals and antennas for it,
you should visit www.uhf-sat.com

'The page cannot be displayed'

Sorry about that TG, its www.uhf-satcom.com

Regards
Brian

On Feb 26, 11:49 am, "Greg" wrote:
I'm a newbie upgrading to a 3GHz scanning system so I'm no looking round for recommedations and feedback on antennas that perform
up to 3GHz. I would rather spend extra for a professional level antenna than go for a cheaper option. The AOR DA5000 looks good
but I'd appreciate any tips before I start shelling out money. I'm currently scanning with a D130 discone which works well but it
only goes up to 1300MHz. Thanks for any advice.

You will be lucky if you pick up ANYTHING worth listening to above 400Mhz
R

There's alot around 400-500 as steve terry said in his reply,
and around 800-1000 there's alot of analogue repeaters,
shortrange stereo wireless/headphone, and cordless phones

Also there are point-to-point links above 1000MHz, used between base
stations and hilltop radio sites. You can spot these on masts by the
horizontal plastic tubes pointing outwards, these contain a long Yagi.
The small elements for these wavelengths are more affected by wind &
rain, hence the protective tube.

AFAIK these carry plain FM voice if it's a single-channel link, multi-
channels using subcarriers also exist.

In article
,
"alexander.keys1" wrote:

On Feb 26, 11:49 am, "Greg" wrote:
I'm a newbie upgrading to a 3GHz scanning system so I'm no looking round
for recommedations and feedback on antennas that perform
up to 3GHz. I would rather spend extra for a professional level antenna
than go for a cheaper option. The AOR DA5000 looks good
but I'd appreciate any tips before I start shelling out money. I'm
currently scanning with a D130 discone which works well but it
only goes up to 1300MHz. Thanks for any advice.

You will be lucky if you pick up ANYTHING worth listening to above 400Mhz
R

There's alot around 400-500 as steve terry said in his reply,
and around 800-1000 there's alot of analogue repeaters,
shortrange stereo wireless/headphone, and cordless phones

Also there are point-to-point links above 1000MHz, used between base
stations and hilltop radio sites. You can spot these on masts by the
horizontal plastic tubes pointing outwards, these contain a long Yagi.
The small elements for these wavelengths are more affected by wind &
rain, hence the protective tube.

AFAIK these carry plain FM voice if it's a single-channel link, multi-
channels using subcarriers also exist.

Actually, Most of these antennas you describe are Circularly Polarized,
Helix antennas, inside the RayDomes.

You wrote in
:




Actually, Most of these antennas you describe are Circularly
Polarized, Helix antennas, inside the RayDomes.

I thought it was "radomes", from radar.

--
Percy Picacity