I cut mine down to 13" and then used 2 plastic black screw protectors which I bought at True Value hardware and super glued them on to the ends.

 

So for those of you who have whacked your CB antenna and might possibly sell your bike later on; are you gonna disclose what you did to the new owner, or salesman, or just let the new guy fry his CB radio if he decides to use it?

Just a thought; if you ever ride in a group where other bikes are equipped with a CB, the ol' CB can be right handy! And depending on the company you keep, pretty entertaining at times as well.

 

... You don't think they will notice that the whips are 2 feet shorter on their own?

 

Just do this:

 

You just read this thread and asked if any one will notice? They might, but would they think anything is amiss? A CB antenna can be as short as 2ft if it is loaded right. J&M sells the "shorty" as does the MOCO. If you have people so uninformed about a CB as to ask if they can cut the antenna, what makes you think they would think anything is wrong if their "new" bike has shorter antennas than another bike?

Course, unlike a lot of folks, I believe in full discloser when I sell something......that is how I want to be treated....sadly a lot of folks believe in the "buyer beware" philosophy.

 

Cutting down your am-fm antenna will only raise it's resonant frequency on the fm band away from its original frequency. Most vehicle antennas are designed to resonate at the center of the fm band which is 98 mHz, 88mHz being the low end, and 108 mHz being the high end for a total of a 20 mHz bandwidth. The trade off is a 'less sensitive' antenna the further you get away from 98 mHz. Shortening your antenna will just make it more 'sensitive' higher up the fm dial. As for the am band, the antenna would need to be thousands of feet long to resonate anywhere near the center of the am band. In reality the antenna looks like a toothpick in length to those very low am frequencies, so trimming it will have little effect on the am band. The only reason am works is that the commercial am band is so low in frequecy the signals will travel up, down, and around the hills, literally following the curvatures of the earth. This is unlike the fm broadcast band which at the higher vhf frequencies sends the signals out in a straight line with no curvature or bending of the signal, usually out to the 'radio horizon' of about 25 miles when transmitting a few feet above earth. AM broadcast transmitters require fifty thousand, to hundreds of thousands of watts just to cover a primary footprint of an average city, whereas a commercial fm station can just use a few thousand watts but must have their transmitting antenna at a great height overseeing the city or area they wish to penetrate and cover.
So, if you live and drive around the primary footprint of your radio stations coverage area, then trimming your antenna will have very little effect on your receive abilities. It's only when you get away from the stations intended primary footprint and out into the secondary or tertiary footprint's lower signal levels that you'll need all the help (sensitivity) that you can get from a properly tuned antenna. Bottom line is, if you like to travel out into the boonies and still listen right to the raggedy edge of the radio's ability, then don't touch the antenna. However, like I said earlier, if you're just motoring in and around your primary coverage area then trimming down you're antenna will make very little difference.
Now, onto cb's. If your talking about cutting down the length of your cb antenna then that's a different animal, don't do it! Cutting down an antenna that's made to match up to a transmitter will create 'standing waves,' which in simpler terms means a radio signal that can't leave the antenna because it's not tuned or resonated properly. So all that transmitted energy that can't leave the antenna into the air is reflected back into the cb radio as heat which will destroy your cb's amplifier output stage. In some of the better designed cb's there is a foldback circuit which will severely limit the transmitter's power when it senses a badly matched antenna. Either way it means a very reduced range from your cb.

 

Got that right! As delivered, the 2014 CB antennas resonate somewhere around 25 Mhz and will measure an SWR of more than 3:1! Taking about 6" off the 2014 CB antenna will probably bring the SWR down to about 2:1 (an improvement in performance compared to stock length).

 

When transmitting, the transmitter sees no transition from the antenna to free space. The antenna design in all respects is determined by freq. Any alteration to the antenna results in the rf from the transmitter being reflected from the antenna back into the transmitter. The degree of reflection (standing wave ratio, SWR) reduces the strength of the radiated rf to free space, seriously reducing the range. The ideal is to have as much peak forward power and as little SWR as possible.

 

Sounds like you understand SWR theory. Maybe HD could use your help? They certainly don't seem to understand "The antenna design in all respects is determined by freq." as you put it. If they did, they wouldn't use a Motorola connector (typically used for 75 ohm antenna systems) in a 50 ohm coax CB antenna system. And that antenna system wouldn't be found resonate a full 2Mhz BELOW the 27Mhz CB band. The '14s need a complete redesign of the CB antenna system...

 

i'd bow to Merrill (Skolnik). ha!