back of set antenna for an 898t?(or any simple indoor antenna actually)

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eahuntley

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I'm looking to upgrade the antenna on my 898t, but I really don't use it enough to warrant setting up a discone or any type of outdoor antenna really, and I don't have an attic available, so I'm looking for an alternative.

Right now I've got a mobile magnetic "hershey kiss"(I think it cost about $10) mounted on top of it, and it's a little better than the stock antenna, but not by much. I mostly monitor 800mhz. I tried mounting my radioshack 800mhz antenna to the back of it, but I had to put together a right angle adapter to get it to stand straight up, and it really didn't work that well(might have just been because of the adapter)

So, does anyone have any ideas??
 

RoninJoliet

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The only increase in signals you would receive would be up in the attic or better yet on the roof with RG6U lowloss coax at the shortest length possible for 800 as the longer the coax the more loss of signal...I use the small $25 RS groundplane in the attic with 30' of RG6U=great reception....
 

CompuDoc

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Why not take the mobile antenna you have and just mount it outside somewhere?. Years ago I had a magnetic mobile monitoring low band and just placing it outside helped.
 

ArtU

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My trick with the candy kiss antennas inside is to mount them on a can of peas or corn; and move them to the window ledge with the coax going to the scanner. This helps quite a bit really easy.


Art
 

frankcastle

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My trick with the candy kiss antennas inside is to mount them on a can of peas or corn; and move them to the window ledge with the coax going to the scanner. This helps quite a bit really easy.


Art
Will it make a difference if the corn or peas is DelMonte or Jolly Green Giant?...lol
 

antennaboy

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Digital Radio Is Comming To Australia

Do anyone know what so special about digital radio

why is it suposed to be better... is it just sound quality or somthing else


Andrew from tvantennasperth.com.au

Thanks For Sharing The Knowledge! :Mrgreen:
 

ArtU

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A can of vegetables creates "0" ground plane.... none. A brief lesson in antenna theory is in order: Ground plane - Wikipedia, the free encyclopedia
Hi Steve, That is not correct at "0" ground plane. Sorry a can does create a ground plane even at frequencies near UHF it creates a ground plane close to 6 inches.

At 700-900mhz how long of the wavelength is the can of peas acting as the reflective device to the quarter wave kiss antenna? How exact does that have to be for receive vis-a-vis transmit?

Wiki Here:
In VHF (30 to 300 MHz or wavelengths 10 to 1 meter) used in mobile communications, the metal of a car body begins to act as an efficient quarter-wavelength ground plane.
Lets rebut the Wiki here. The car is great at 10/11 meters. However, the ideal ground plane for a 2 meter 145mhz transmission is not an entire car or truck. We all know the size of a 1/4 wave 2 meter ground plane is an order of magnitude smaller then a car ;)

By the upper VHF and UHF (300 to 3000) MHz frequencies, the car or truck body ground plane can be several wavelengths long, making an "ideal and lossless" groundplane.
The 1/4 wave ground plane for 433.920 is how small?
By the time you get to 2468mhz the perfect 1/4 wave ground plane is how small?

Back to ~800mhz and how many wavelengths a can of peas really is and how exact compared to that wiki information it needs to be to provide a receive only ground plane?

A 1/4 wave ground plane is as wide as the antenna mast is tall, or if a vertical dipole match like the can of peas at ~800mhz , the ground plane is as long as the antenna mast is tall.

At 900mhz a wavelength it is approximately 33.4cm or about 13 inches and lets divide by 4 and get ~ 3.25 inches.

A can of peas is about 1/2 wavelength and for receive purposes is a great base weight to keep the magnetic kiss antenna stable as well as acting as a gounrd plane.

Remember, while transmitting antennas and ground planes need to be exact for good swr;while receiving you need a good ground plane and a reasonable antenna match but does not need to be perfect. they can be 1/4 wave, 1/2 wave, 5/8 wave and all have good receive characteristics.


Art
 
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