Making an antenna

[JediMaster]

I would like to make an antenna for my scanner. I've posted about this before. I want an antenna for my scanner that will pick up everything from the CB band to the 800MHz band. Basically I want to make a Long John antenna. I don't feel like paying the price for it and I need to mount it special on my SUV so I have to make a custom bracket anyways.

So my question is, the Long John states it is 51 inches long. I take it that it would be exactly 51 inches. Is there anything special I need to use to make the antenna or would just a good piece of metal rod work well? Also, do I have to have the cable from the antenna to the scanner any certain length?

 

[N_Jay]

I would like to make an antenna for my scanner. I've posted about this before. I want an antenna for my scanner that will pick up everything from the CB band to the 800MHz band. Basically I want to make a Long John antenna. I don't feel like paying the price for it and I need to mount it special on my SUV so I have to make a custom bracket anyways.

So my question is, the Long John states it is 51 inches long. I take it that it would be exactly 51 inches. Is there anything special I need to use to make the antenna or would just a good piece of metal rod work well? Also, do I have to have the cable from the antenna to the scanner any certain length?

JediMaster, is yet a grasshopper in antenna design.

Much there is for you to learn for not your antenna to be more than implements of the dark side. Yes, there is, Ahhhh

 

[kd4jxz]

LOL @ N Jay :lol:

 

[thumbtrap]

Obiwan thinks he knows much instruction about. Yet he may know antennas backward and forward does he, but teacher he is not. Must go and seek the seer Google. Google knows nothing, but hears all. Google thinks you want to buy, yet learn you may if you wade through the spammers yes.

A multiband whip is probably not something you can make as well as you can buy - however a discone you probably could. For a vehicle install I would definately buy. If only because of the commercial mounts.

 

[INDY72]

Ahh i sense much frustration in you yesssss. For VHF Lo Band coverage, minimum of 36 inches of steel whip with 2 inches of coil will you need,.. for VHF Hi band minimum of 28 inches of whip with 3 inches of coil help you it will. Now young pattawan to UHF we go yessssssssss. Beware the lack of coilage especially into the lack of coverage it will lead yesss.

 

[JediMaster]

But if you look at the oh might Long John antenna it is 51 inches straight up of nothing but steel. No coils or anything special. So how could that be so hard to make?

 

[INDY72]

Because my young apprentice the long john is NOTHING SPECIAL LOL,... It is just a CB antenna hooked to a scanner. A properly designed scanner antenna has not only element (whip) cut to specifically match the bandwidth you want to recieve, but also most have a coil designed to improve the gain on bands you want. A good scanner ant is designed very closely to actual broadcast ants for the bands you want to hear.... For VHF Lo Band, sure a great big long chunk of steel is all you really need. But for great reception on other bands you want it more specifically designed to be effective at those bands. It is usually best to just buy a good all band discone, or the like that is already designed for multiband reception,.. My personal theory is that you get the ant designed for the band you most often listen to. Example: You mainly listen to UHF/VHF Hi,... a good UHF designed ant will also work good on VHF Hi, and will aslo do fairly well on 800. But if your mainly into 800, then no that a good 800/900 ant sucks on VHF Lo,... but can do OK on VHF Hi,... depending on how close to the system your listening to you are.
Look closely at the multiband ants at Waltel, and other places,... there are several good ones out there. (Where I live there is an Police Department that uses NMO Magmounted Dual Bands from Waltel-VHF Hi/UHF for thier actual units untill they put the units in the radio shop for NMO permanent ants.)

 

[JediMaster]

I know antenna for each band need to be different. And I know a discone would be the best option. However, I highly doubt a discone would look good on my SUV. Right now I have the radioshack telescoping antenna and it works wonderfully on my Pro-95 scanner. However, alot of times I get too much static unless I hold the antenna out my sunroof. Therefore I want to mount a permanent antenna on the outside of my car that I can just connect to my scanner when I want to use it in the car. I listen to all the bands on my scanner from the CB (because my CB radio doesn't have a scan function) to the 800MHz (where I work.) So, give me some ideas on what i can do.

 

[N_Jay]

I know antenna for each band need to be different. And I know a discone would be the best option. However, I highly doubt a discone would look good on my SUV. Right now I have the radioshack telescoping antenna and it works wonderfully on my Pro-95 scanner. However, alot of times I get too much static unless I hold the antenna out my sunroof. Therefore I want to mount a permanent antenna on the outside of my car that I can just connect to my scanner when I want to use it in the car. I listen to all the bands on my scanner from the CB (because my CB radio doesn't have a scan function) to the 800MHz (where I work.) So, give me some ideas on what i can do.

If you don't want to buy a multiband scanner antenna, then I would use a VHF low band whip without any tuning coils.

Tuning coils and the associated capacitors will greatly limit the frequency range of the antenna. A 50 MHZ whip (about 1.5 meter long) will do a decent compromize.

I don't know what a "Long John" is, but it makes no sense to be a CB antenna at 51" without a tuning circuit (coil or capacitor) of some kind.

Another antenna that might work OK is a top loaded CB antenna, as the coil will not have any effect at the higher frequencies and the bottom whip part should still be fairly long. (just guessing here)

 

[thumbtrap]

I have a glass mounted cellular antenna hooked to my BCT8 - because I'm primarily interested in an 800 mhz trunked system. (I'm going to try a trunk lip mount with some gain - listening ON 800 mhz, I don't get the benefit of hearing the other mobiles in the field from a repeater like what goes out on the broadcast only UHF frequency.) It is indeed atrocious in the low bands. Nonexistant is more like it. I agree - discones look ugly. You might as well make it into an antenna farm rather than put a single discone if you're trying to avoid appearing hamsexy. OTOH - it might keep people from driving 53 mph in front of me when they see the 800mhz antenna and a Wheelen Talon and can't tell what color it is.

 

[INDY72]

What kind of ant you got hooked to your CB? And more importantly,.. where is it mounted? You could go for a Lo Band ant mounted to correspond to your CB ant,.. IE- scanner NMO perm mounted right in front of your CB ant, if its roof mounted. Or if youve got it side mounted go for a center roof mounted NMO perm for the scanner anyway so you get decent omnidirectional coverage. The best I have seen are the ones from Waltel. SUV's are hard to play around with as far as ant's,... Do you need to have it lo-pro for parking garages,... or can you have it waving high and proud on the roof? If lo-pro then youll need to set up iether some kind of ball mounting on the side (opposite your CB ant) or rig a mirror/hood lip mount. Just know that with a Lo Band ant,.. your 800 coverage will be lousy. So as stated before,.. your best option in my opinion is to get a UHF type as it would put you in the middle ranges of the freqs you want and will give you decent coverage on all bands. (Not to mention that with a cool ant configuration, not only do you get good coverage, your ride also looks good.)