Making Antenna

When making antenna out of wire, does curling it affect the outcome?

I want to make an antenna out of wire. It's a 433 MHz Antenna used for RF. The wire is made out of components of a cat-5 (Ethernet) cable. Instead of leaving the wire straight out, can I just curl it?
When I mean curl it, I mean make them into coils.
Is there any explanation why there is no difference please?

Curling it does have an effect. What it does is change the inductance. The effect of this is to change the resonance point of the antenna. In other word, to get it to resonate on the same frequency you would have to shorten the antenna.

It also has an effect on the aperture of the antenna. A shorter antenna does not 'cut' the same amount of field and so the induced voltage is lower. In other words, a shorter antenna is not as good as a full length antenna.

2008-11-28 22:24:00 by wildgooseneck

I like to take broken thins apart and fix them or make new things out of them. and right now im fixing a broken wifi adapter.

but some things i use as an antenna dont work as good as others, does it matter what metal i use or how big it is, or what?

The type of metal doesn't matter but the length does as the length has to match what frequency the antenna will be used on to get a good SWR (standing wave ratio). For 2.4GHz WiFi the antenna must be 1.2-1.22" long for quarter wave, 2.4-2.44" for half wave or 4.8-4.88" for full wave. I myself have modded a 3Com 3CRWE737 with just 2 lengths of solid core phone wire which I cut to 5" and then started trimming some off the end a little at a time until the signal strength peaked and then dropped back down a notch. I did this with the network set for channel 1 so that the wires would be slightly too short for that channel but would be just right for one of the higher ones. I have provided a link that shows how to make a directional antenna out of a Pringles can and gives the formula to get the proper length from the frequency. FWIW the full wave antenna length for a TV on channel 3 would be about 187 inches which is 15' 7".

2007-12-28 18:34:12 by chrisp p

Price: $17.95 $7.79

Fits any 3.5-millimeter external antenna jack
Includes adapter plug
Extends to 23 feet and can be easily rewound into its compact case
Has 3.5-millimeter mini plug
Improves the performance and reception of your shortwave radio

The antenna has been making sounds for awhile and I don't know how to turn them off. SOmetimes it will turn off by iself but it takes forever. How can i disconnect it my self without taking it to a car place and paying them a bunch of money to disconnect it?

If it is stuck in the up position, just unplug the antenna motor that is located in the fender.

2007-09-04 19:43:18 by Micki H

Price: $19.95

Using about 30 feet of RG6.
Making a vertical ground plane antenna for APRS.
Will be using about 40-45 watts.

The problem I see here is that ham radios are 50 ohm devices. So are the antennas. 144.39 is in the ham 2 meter band. Using 75 ohm cable may not work well. 75 ohm cable is used for TV operation.

2007-09-01 17:11:32 by Mc G.

I have a single wire for an antenna, but it doesn't get the best reception. Should I just use a longer wire or do they make an antenna that connects with a single wire?

Hiya

It depends upon what sort of radio you have to listen to .
Is it a AM , FM , or Shortwave radio ,,or other ?

Depending upon the radio frequency will determine what is the type of antennas that you can use.

A different sort of antenna would be required for improving reception on the FM bands , than it would do on the SW bands.

The site http://www.swdxer.co.nr/ has many ideas on shortwave antennas if that where your interest is in.

2007-09-20 20:34:10 by S R