46.46MHz Wavelength?

[rescue31210]

Hello,

Can anyone tell me what the approximate wavelength is for a 46.460MHz Frequency?

Also, how tall (In inches) should I cut the antenna for monitoring 46.000MHz to 47.000MHz?

I'll be using a Motorola Maxtrac Lowband.

Thanks.

 

[N4JNW]

Full wave is 20 ft, 1 25/32 inches.

Half is 10 ft. even

Quarter is 5 ft. even

If you want to monitor 46 to 47 Mhz, cut the antenna for 46.500, which is close to the measurments I gave you above.

 

[rescue31210]

Wait, I don't think I fully understand.

My antenna's for CB Band.

It's 29 1/2 inches long.

How long should it be for 46.46Mhz?

Thanks, sorry for the simpleton question.

 

[N4JNW]

What kind of CB antenna?

 

[N4JNW]

In this case, best you could do would be 1/8 wave. That would be 2 ft, 6 1/4". if your CB antenna has a loading coil, which I'm sure it does being that short, you'd need to remove the coil, and bypass it with a single piece of wire.

 

[N0GX]

your cb antenna would have a coil in it to make it shorter. a full quarter wave for cb would actually be around 9 feet, but the coil make it shorter.

 

[rescue31210]

I have this antenna:

http://www.radioshack.com/product/i...kw=cb+antenna&kw=cb+antenna&parentPage=search

No, it doesn't have a loading coil.

 

[N4JNW]

Yes, it has a coil. It is in the thicker base, just above the magnet.

 

[rescue31210]

Yes, it has a coil. It is in the thicker base, just above the magnet.

Oh, ok then.

What should I do?

I can put this antenna on a base with no coil.

Now it's just the mag-mount, and antenna. How long in inches should the antenna be for 46.46Mhz?

Thanks.

 

[N4JNW]

2 ft, 6 and 1/4" from top of magnet to tip.

 

[rescue31210]

2 ft, 6 and 1/4" from top of magnet to tip.

Ok, done. We'll see how it preforms. Thanks alot for the help!

 

[N4JNW]

No Problem dude.

 

[k9rzz]

Full wavelength (in feet) = 936/freq (in Mhz) 936/46.46 = 20.15 ft
Half wavelength (in feet) = 468/freq (in Mhz) 468/46.46 = 10.07 ft
Quarter wave (in feet) = 234/freq (in Mhz) 234/46.46 = 5.04 ft

John K9RZZ

 

[phoenix]

never mind

 

[gcgrotz]

If you're planning to transmit with that Moto, I would stay away from the coil-loaded RS CB antenna, you will likely burn up the coil. If you can't use a full size 1/4 wave, which will work VERY well, then you should get a commercial antenna with a coil designed for 42-50 MHz.

I have a RS full sized whip and ball mount on the bumper cut for 50 MHz for the ham band and it works well on 46 MHz. The local fire dept used 46.46 until they went to 800 last year. Which fire dept are you monitoring?

 

[N_Jay]

2 ft, 6 and 1/4" from top of magnet to tip.

How did you figure that?

 

[rescue31210]

If you're planning to transmit with that Moto, I would stay away from the coil-loaded RS CB antenna, you will likely burn up the coil. If you can't use a full size 1/4 wave, which will work VERY well, then you should get a commercial antenna with a coil designed for 42-50 MHz.

I have a RS full sized whip and ball mount on the bumper cut for 50 MHz for the ham band and it works well on 46 MHz. The local fire dept used 46.46 until they went to 800 last year. Which fire dept are you monitoring?

I'm in Suffolk County, NY. There's not just a fire department, theres 109 of them.

I don't want to transmit on the channels, I'm going to use it for RX only.

When I'm in my fire department, our radios pick up all of the other departments very well. However, my Lowband radio cant pick up crap!

So, here's my question: I'm very short in cash, can anyone lead me to a Lowband antenna that will pick up exceptionally well on 46.46 and 46.44MHz?

Appreciate any help!

 

[mancow]

In all reality any decent CB antenna should work adequately in a receive only application.

 

[k9rzz]

I'm in Suffolk County, NY. There's not just a fire department, theres 109 of them.

I don't want to transmit on the channels, I'm going to use it for RX only.

When I'm in my fire department, our radios pick up all of the other departments very well. However, my Lowband radio cant pick up crap!

So, here's my question: I'm very short in cash, can anyone lead me to a Lowband antenna that will pick up exceptionally well on 46.46 and 46.44MHz?

Appreciate any help!

A 2 meter 5/8 wave whip should work fine right out of the box.

John K9RZZ

 

[K2GOG]

A 2 meter 5/8 wave whip should work fine right out of the box.

John K9RZZ

i agree. a 2m 5/8 is close to a 1/4 wave on 6m. I am surprised it took this long for someone to mention it. haha.

It still could not hurt to check it with an antenna analyzer or VSWR bridge to make sure the SWR is as low as possible. Not that it matters much on receive only, but if that radio can transmit, better being safer than sorry if it "accidently" transmits at some point.