Antenna placement effects on power output

[troyboy162]

http://kv5r.com/ham-radio/mobile-antenna-placement/

I found this page pretty neat. The Things its showing are not universal of course but still good info.
-3db more or less equals a 50% decrease in power

[Seanz0rz]

I'd love to mount mine on center of the roof, but I'm not sure how that would do with my roof rack.

Right now I receive great, but I feel my tx could be better. Maybe I'll look into moving it.

[4x4mike]

On KV5R and some other pages there is some info on db. For the most part db are like HP on things from vacuums to compressors. What isn't explained in most products is the dbd or dbi. They are different and can be determined by the antenna placement and ground plane or lack there of.

I was recently in the market for a couple new antennas. I wanted a dual band with higher gain. After researching it seemed my ultimate best bet would to use both of my already installed NMO mounts for a single 2m antenna and a single 70cm antenna with a duplexer. Running such a set up would get around the short cuts a lot of manufacturers use in dual band antennas and their coils. It was explained that they are cheating physics and wavelength is a real world player in the game.

As such I get best results from a single 1/4 wave 2m antenna (Larsen NMOQ, tuned to 147 mhz) as I have the necessary ground plane. My B-10 dual band antenna does the job for both bands but has zero gain on 2m. I've learned this is not a problem for most of my radio use. In the real world my 5/8 wave 2m whip shouldn't be much better for most situations than the 1/4 wave.

Sean, I think that your high mounting location and with the Larsen 2/70 you've got a great setup. The 2m portion of the 2/70 is 1/2 wave which doesn't require a ground plane (which I believe your rack is lacking). As a backup/spare/alternative look into just a 2m, 1/2 wave antenna. It might be a little shorter than the 2/70 but just mono band and you don't have to worry about the ground plane. Most soft top/roll gaged/tire swing mounted antennas should be 1/2 wave. Here is a good example: http://www.ruggedradios.com/index.php?main_page=product_info&cPath=182_183&products_id=416

Another thing to consider is the power you're sending through a whip. Higher power can cook a whip in short time. Higher quality antennas last longer and do better but over time they lose their structure due to heat.

Antenna location can determine radio performance. The mount and antenna also play a roll. This is copied but most explanations are about the same:
"Gain is reported in two general units, dBd and dBi. They differ from where the point of reference is. dBd is just over 2 units smaller than dBi when the exact same thing is being reported (it's kinda like feet vs meters). If they don't indicate what unit they're reporting the values in, assume it's dBi so you don't get fooled into getting the lower gain antenna after the marketing folks do their magic.

dB gain is an important spec on an antenna, but don't get too caught up in the "bigger is better" mess. 3 dB = double the signal, 6 dB = 4 times the signal, etc. That sounds like quite a bit of additional signal doesn't it? The fact is that 1 "s" unit (the values on many signal strength meters are shown in "s" units) is 6 dB. The extra 3dB will only change a weak signal from extremely noisy to very noisy. A strong signal will change from fully quiet to ... wait for it ... fully quiet (yes, no change at all).

The additional signal may even make things worse if you're in an area of heavy RF. The strong signals may mix together giving you what's called intermod, a signal being received on a frequency where it isn't actually being transmitted.

Generally a "no gain" antenna would be 0 dBd or 2 dBi. 3 dBd is generally pretty modest while 6 dBd is fairly high (on a mobile antenna)."

[troyboy162]

Sean we've got to try some more tests. On 395 I stopped receiving you around the same time as the hand helds. Of course that was miles and much better then cb.. . We oughta check it again some time. About the time I lost you I tried Keller peak and got 5x5. That's apples and oranges but if everything checks good we can still use far away repeaters to make up for a possible line of sight issue.

[Seanz0rz]

I'd like to get a meter on my setup and see what I'm getting. Might need to adjust the antenna. I still need to get a short antenna for the tighter trails, too.

[4x4mike]

K0BG is another great source. Here is an applicable link.

http://www.k0bg.com/myths.html

[Kryptoroxx]

Forgive me first of all. I am very ignorant on this subject as said before. I have installed CB in my 4runner already. What are the advantages of HAM over CB besides distance? I know about the license but beyond that it's all greek to me I'm afraid.

[troyboy162]

clarity is the best part I think in respect to 4x4 use. The repeaters and great distance are wonderful but understanding everything that people are saying because the voices are clear is awesome.

[Seanz0rz]

I'd say 3 things: As Troy mentioned, Clarity and Range. Also, a distinct lack of asshats. You don't typically have people pumping thousands of watts of power cussin' and fightin' on the airwaves. It is a much more civilized place.

Also, so many more channels. Hundreds (over 70cm and 2m bands) compared to the 40 on CB.

You can also get small, inexpensive handheld units that don't suck, unlike handheld CB radios.

[Kryptoroxx]

I'd say 3 things: As Troy mentioned, Clarity and Range. Also, a distinct lack of asshats. You don't typically have people pumping thousands of watts of power cussin' and fightin' on the airwaves. It is a much more civilized place.

Also, so many more channels. Hundreds (over 70cm and 2m bands) compared to the 40 on CB.

You can also get small, inexpensive handheld units that don't suck, unlike handheld CB radios.

You had me sold at the reduction of asshats lol. I will go do some reading and see how much a mobile setup might run.....or maybe a handheld. I have no idea.

I am guessing my firestik 4ft will not work with ham?

stamped and snail mailed

[Seanz0rz]

Nope, the firestik is CB only.

You can find good used equipment. Ham radios are typically much better built than CBs.

QRZ has a classified section: http://forums.qrz.com/forumdisplay.php?7-Ham-Radio-Gear-For-Sale

or you can roll the dice on eBay. Yaesu, Kenwood, and Icom seem to the be the winners. I love my Yaesu but might get a Kenwood later down the road.

As discussed around here, the Baofeng UV-5R is a great HT radio. I have one and will be buying a second soon. They are by far not the best radios, but they work well, especially for the price.

[Kryptoroxx]

Sounds like I need to some serious reading lol. I have time to do some research on it while I count and save pennies for welding tools.

[Seanz0rz]

Yeah, I think we might throw a ham FAQ together for the site. Really focus it on what mist of us use it for, and not a lot of the more hobby related topics.

[4x4mike]

HAM is great if you're traveling with others that run it as well. It took a couple years before I could get wheeling buddies to jump on board. Although I use it for things other than wheeling it's nice to have everyone on the same type of communication. CB is still used a lot on trails and I think still a valuable item to have when traveling especially on trails that are also used by enthusiasts.

ICOM and Yaesu make decently priced mobiles that have useful features (like a forward firing speaker or high output or size). The exam is easy and there are links here in the communication section about what you need to do. A handheld radio is also useful but very limiting due to it's power output and depending on the the model of handheld the antenna and/or available antennas. If you're in a group on a trip you can get away with an handi talkie and mag mount antenna. Adding a battery delete with full time power and a hand mic you'd be happy but have a lot of wire running around.

FWIW a decent hand held maxes out at 5 watts (fast battery drain at this level) whereas a mobile radio has a low setting around 10 watts.

I've got a Yaesu FT-2800 and an FT-8800 as well as assorted handi talkies. Sean runs an FT-7800, Paddlenbike an FT-1900 and Troy a Kenwood I believe. Lance has a Kenwood TM-D710A. So feel free to ask questions or search for our radio posts.

I currently have the 8800 in the 4Runner and if I had to do it all again I'd still have the 8800. If the TM-D710A was much smaller it would be a contender but the size and complexity of the radio (even for small things) makes it a tougher choice. Yaesu's are easy to navigate and have intuitive menus.

[troyboy162]

sean that sounds pretty good. Something simplified so its as easy to understand as CB. Its such a huge topic if you google and it doesn't need to be.

[Kryptoroxx]

Yeah, I think we might throw a ham FAQ together for the site. Really focus it on what mist of us use it for, and not a lot of the more hobby related topics.

I like that idea too. If you need a gunea pig for reading through it I can volunteer lol.

Sent from my SAMSUNG-SGH-I727 using Tapatalk

[Kryptoroxx]

Yeah I have been reading for the better part of today when I get the chance and there is a lot of ground to cover. A lot of it is dealing with stationary setups. I understand to a point I suppose. I am somewhat familiar with HAM though by being in the military but lets just say I can talk on radios....but I don't know what makes them tick lol. You can drop a lot of money very quickly on some of this stuff. I would say a solid HAM hobby would rival a rock crawler any day of the week lol. I was taking a gander at the Yaesu 8800 and 7900 as the price seems fairly reasonable and they have good capabilities from what I can tell. Of course there isn't anything stating that it's a DIN or Double DIN installation. I have no idea how big these radios are.

If I'm not mistaken these radios are very similar as far as programming channels in. Once you know what band you're on and what freq they are on then it's a matter of plugging in the numbers and presto. You're in. My dad is big into this stuff and I'm afraid that I only get to see them every 3 years or so just because of logistics and the fact that I am kicked around the globe like a soccer ball.

Now I have an extremely random question about call-signs. In the military world when you're talking within your unit various handles are used to identify individuals. Some....wait....most of them are either highly motivated and violent or cheeky and funny if you know the person. Can those be used on a Ham net?

[Seanz0rz]

You won't find a din or double din radio (at least one that you'd want to buy). You can make a custom mount, but my preference is to mount the body somewhere else and put the faceplate somewhere convenient (if it has a removable faceplate).

I'll toss something together soon, hand it off to Mike and Troy for review and then we will post it.

As for call signs, not really. you will be assigned something like XX#XXX, KK6BQA is mine. You can apply for a vanity call sign, but it will just be letters and a number. That being said, on the trail, especially in informal groups, we just use first names and rarely, if ever, give a call sign.