Simple directional antenna suggestions ?

[1BMG1]

Have a Radio Shack PRO 18 with the 800Mhz ducky. Works pretty well, but my local Police, Fire, etc went to EBRCS and of course, at times, my scanner has difficulty receiving the multiple transmissions on the same frequency (simplexing ?).

Heard that "directional" antenna might be a good solution. I have NO problem with range, and I'm in an area with strong signals overall, with a lot (too many in my case) of transmission sites.

Question : can anyone suggest a simple and relatively inexpensive directional antenna that I can experiment with ? Might initially just use it inside the house until I get a feel for whether or not it helps solve my particular issue, so small size would be good.

Or... is there anything else you might suggest I try to make these particular transmissions more understandable ? PS - Already tried stubby (nascar type) antenna - no real difference though.

thx

 

[rescue161]

Just make a Yagi out of a broom stick (or piece of wood or PVC or aluminum) and a coat hanger (or wire or metal - anything that will conduct electricity). The more elements you use, the more directional it will be. There are TONS of simple plans for Yagi antennas.

I made a 3 element Yagi out of aluminum that I bought at the hardware store and it works great. The boom is aluminum tubing and the elements are aluminum rod.

 

[prcguy]

Ebay has a bunch of 800MHz Yagi's for under $20.
prcguy

 

[davenlr]

If you are wanting to build something yourself to experiment with, try a quad loop (1 wavelength of wire in a square). Feed it with 50 ohm coax on one of the vertical sides. It will exhibit very sharp nulls off the sides (when the loop of pointed at the transmitter). By rotating the loop around, you may be able to null out the transmitter site of your simulcast system that is coming in at the same strength as another, while boosting the signal of the one you want. If this works, you can add a second loop 5% larger spaced 0.2 wavelength behind the main loop, and it will give you about 5 dbd gain in the forward direction, enhance the null off the side, and give you really good rejection off the back.

Another trick would be to try using a UHF tv antenna, like a small 2 or 4 bay bow tie type. Remove the mounting tabs that hold the U bolts to the screen, and rotate them 90 degrees so when you mount it, the bows will point up and down, instead of horizontally. Trim the bows so they more adequately cover the 800 Mhz band (older ones will work as TV channels used to be up in that area, and the antenna should cover it). Feed it with 75 ohm coax through a 300 to 75 ohm TV balun. They are quite directional, and you should find several good nulls off the sides and back to cut out the offending transmitter site.

 

[popnokick]

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+1 on TV antenna.