Batboard

Does anyone have a recommendation for a UHF (460mhz) antenna that could be used inside a 200,000 SF 3 story building? I'm looking for something that I would be able to install in a suspended ceiling. For reference, a 3db gain collinear mag mount mobile antenna almost does the job with a few marginal areas. One potential antenna is a Larsen FB2450 which is a 32" high base station model that would fit in the ceiling space. The repeater is putting out 10 watts.

Have you tried hanging the antenna upside down from one of the steel beams? Many of the lower cost antennas have
a high angle of radiation and do poorly right under the antenna. The next type of antenna to consider is some
leaky coax and run it vertical in the building. Many people run the coax down the elevator shaft in the center
of the building. This will have to be a plenum rated cable to meet the fire code. This way you get a fairly
even level of RF on each floor. Don't forget to terminate the cable with a 50 Ohm load at the far end.

Jim

ChrisNYC wrote:Does anyone have a recommendation for a UHF (460mhz) antenna that could be used inside a 200,000 SF 3 story building? I'm looking for something that I would be able to install in a suspended ceiling. For reference, a 3db gain collinear mag mount mobile antenna almost does the job with a few marginal areas. One potential antenna is a Larsen FB2450 which is a 32" high base station model that would fit in the ceiling space. The repeater is putting out 10 watts.

We service a hospital that we do half of what Jim suggested...

We have leaky coax on the receive side running down 4 floors and a 1/4~ mounted on the ventilation ducting for the transmit side. 15 watt transmit.

Works well.

ChrisNYC wrote:. One potential antenna is a Larsen FB2450 which is a 32" high base station model that would fit in the ceiling space. .

Most if not all of these type of fiberglass 'base station' antennas have a small diameter steel wire inside them much the same as a mobile so-called gain antenna. No advantage there. They do not even duplex well, either.

Will wrote:

ChrisNYC wrote:. One potential antenna is a Larsen FB2450 which is a 32" high base station model that would fit in the ceiling space. .

Most if not all of these type of fiberglass 'base station' antennas have a small diameter steel wire inside them much the same as a mobile so-called gain antenna. No advantage there. They do not even duplex well, either.

I believe the FB2450 is metal with ground radials and a coil wound in the middle of the radiator. At least that's what it looks like in Larsen's literature:
http://www.larsen-antennas.com/docfiles ... tennas.pdf

ChrisNYC wrote:I believe the FB2450 is metal with ground radials and a coil wound in the middle of the radiator. At least that's what it looks like in Larsen's literature:
http://www.larsen-antennas.com/docfiles ... tennas.pdf

Very poor antenna choice for a repeater.

Will wrote:

ChrisNYC wrote:I believe the FB2450 is metal with ground radials and a coil wound in the middle of the radiator. At least that's what it looks like in Larsen's literature:
http://www.larsen-antennas.com/docfiles ... tennas.pdf

Very poor antenna choice for a repeater.

Thanks for the heads up, Will. Can you make a better recommendation?

ChrisNYC wrote: Thanks for the heads up, Will. Can you make a better recommendation?

Yes, the Comtelco BS450U-C, omni unity gain, gives excellent broad coverage. This antenna is a true center fed one half wave dipole
with a one quarter wave sleeve made with copper tube elements. The actual overall gain is twice that of the FB2450.

http://www.comtelcoantennas.com/PDF%20D ... BS450U.pdf