http://www.worldwidedx.com/cb-antenn...-part-2-a.html Choosing an Antenna
To start this off right, I am
not going to tell you to buy any one particular 'brand x' antenna. I am
going to help make a choice that will work for you. More than that - I will attempt to give reason as to why one antenna may work for you over another. This will include your location, weather, resources, and then cost. I will make some recommendations down the line as well. I will discuss base station setups first; mobile antennas will be considered at the end.
One must keep in mind, that the antenna is the true heart of any radio operator's station. That bears repeating; so read it again. It doesn't matter if you are a seasoned Ham (who know this wheeze well!) - or a newbie who first used someone else's radio before deciding to get your own setup. Because it is what radiates everything
that your station has going on. Linears are great - if used properly; but the antenna is what people hear at the receiving end. A better mic might give you some added character or flavor, but the antenna is at the root that goes between point A to point B. You can still do well on a budget, but I would be lying to you if I didn't tell you that the bettter antenna is the best place to spend your hard-earned cash - first! Don't worry; you will need to spend as much as it takes to do the job right. Sounds fair enough - right?
Let's say that you live in the country - like rural CO, VA, LA, AZ, or even ND or MA. Didn't mean to exclude you if your state wasn't mentioned. Let's say NW Kansas for a start. Relatively flat land, the Earth has decent grounding properties, but the weather can be a real issue. Severe winds, tornadoes (seen them in KS myself!), ELECTRICAL STORMS, and hail/ice/snow. Most rural areas in the US east of the Rocky MTS can be afflicted and influenced much like Kansas is.
You will need to get the antenna up about 30-35 ft
in the air with masting/guy wires - or a concrete-base tower. This is the height you will need before any antenna is attached. Towers are expensive; masting is much cheaper. Of all the environmental threats, lightning and wind will be your biggest considerations. When installing a base antenna, it would be highly advisable to have a friend or two help you. It will make it happen much faster, and be less dangerous that way.
You will need to spend some money on your grounding system. This cannot be avoided at all. It is ESSENTIAL that your station be well- grounded. Three 8 ft
rods in the ground tied together 20 ft
apart in a line with wire bonding between them buried 1 ft
below the surface is a practical setup - about $50-60 with a tailwind. You might have scrap metal that you can work with if you are on a farm, rural home, or a ranch. This will save additional $$$. But this would be the way to ensure an optimal and safer radio station. http://www.worldwidedx.com/tech-repa...and-radio.html
The cost of masting will be dependent if you cannot find used 1 1/2 inch pipe thirty feet long. It need to be stiff enough over its 30-35 ft
length to support itself w/o guy wires when upright; so with guy wire support you should be good to go. Two sets of guy wires with four legs each ninety degrees apart - placed at the center of the mast and at the top - should be ideal. Cost is about $30 if you cannot find a suitable substitute for the guying materials. Be sure that it is firm under wind load - and that if it were to fall over in a severe wind that it will NOT hit a power wire! When anchored securely, this should be able to withstand winds up to 70mph - provided the antenna isn't so massive that it requires more support. If you have to buy masting, it might cost as much as $20 for every ten feet section.
The most common, inexpensive, practical antenna is the 1/2 wave or 5/8 vertical ground plane antenna. They are often made of aluminum and will be 19 to 22 ft
tall by themselves - respectively. The FCC
states that a free-standing antenna can be 60 ft
from ground to tip; so use this guideline to the maximum - I would. If the 1/2 wave antenna you chose is 18 ft
; then you can have masting as high as 42 ft
- provided it is properly supported with guy wires. If you have a 5/8 wave at 22 ft
long; then 38 ft
of masting would be best. If you go over a foot or two - I wouldn't worry about it. The FCC
isn't going to shinny up your antenna and measure the height. Just stay close to tolerance.
Verticals are called 'omni-directional antennas'; they receive/transmit poorly in all directions. I believe that the 5/8 wave vertical antenna is probably the best choice for an antenna. They propagate radio energy better than the 1/2 wave, works extremely well for local communications, and works long distance 'skip talking' with better efficiency. But if you have a 1/2 wave antenna - don't fret. The extra height that you can put it up will help make up a little of the difference.
You might find that if you have more money to spend on your first setup, that you might want a beam antenna. They are the most efficient of all antennas. But there are caveats. They cost more, you will need to install a rotor to change its direction, and you will have to make the masting stiffer. Rotors can be had used/refurbished with the control box from $85 up to $300; a simple $85 one with a single element beam should be more than enough. Beams will have more wind load; which means it will be affected more by the wind than a vertical antenna would be. The BEST part of having a beam antenna, is that the energy from your radio is FOCUSED in one direction. This will help you immensely in transmitting. The cost twice as much as most vertical antennas do - but they are hard to beat. Beam antennas can also get very large and expensive - but even a simple beams works tremendously well. The Ultimate Guide to 11 Meter CB Antennas
Let's say that you live in New York City. Good Luck. You probably live in a multiple dwelling, in which case Landlords have strict rules against such activities. Your best bet is to have a mobile radio and antenna. A magnetic mount antenna can be taken down and put inside the vehicle so that it doesn't get vandalized or stolen. So -you too- have a means to talk on the radio. Some of the better mag mount antennas can talk great distances as well. You can also run a decent sized linear w/o having to put in an extra battery or larger alternator. I know some radio operators that I talk to in San Francisco (50 miles N of my home) who do just that - and transmit very well too. So, you do have some options! This method will work for those who cannot set up a station any ither way.
Many live in the 'burbs' - the suburbs. I do. I have a 5/8 wave antenna that is properly mounted and grounded. As described above - quality mast with guy wires and a decent ground system. A beam antenna may well be my next antenna, because they work better focusing more radio power in a given direction. It may not a new one - but I want to get more usefulness out using just one antenna. But the suburbs can get you into trouble IF you are considering running a linear. I don't use a linear amp; I let the quality of my antenna and its proper installation to make it possible to talk to Quebec, N Canada, Alaska, Hawaii, Mexico, Texas, S Carolina, Virginia, and New York - and everything in between. Goes to prove THAT THE ANTENNA MAKES ALL OF THE DIFFERENCE!
This was written and meant for the beginner.
Tomorrow will be the last part in this series... http://www.worldwidedx.com/cb-antenn...nna-final.html First picture: For reference - to the right is what a tower looks like, and to the left is what a mast looks like. Both the mast and the tower have vertical antennas mounted on them.
Second picture: This is the difference of the radiation pattern of a 1/2 wave and 5/8 wave antenna. Notice that the 5/8 wave moves out far more horizontally across the ground than the (dotted line) 1/2 wave antenna does. Important difference!