FM Antenna on FJR?

I have a regular ¼ wave automotive style antenna on my FJR. It works, but not all that well. Strong stations come in but fade in & out. Moderate stations are barely received. I spoke to a guy at work that is an electrical engineer and he explained that the reason was those antennas are optimized to be mounted on a metal fender and use said fender as the ground plane.

There are different types and brands of antennas out there that claim to be designed for use without a ground plane, such as for a motorcycle, fiberglass boat, etc. Some are passive, some have a built in amp.

Can anyone here recommend one that you know to perform well in our application, on an FJR?

Thanks.

I did a quick Google search on "motorcycle FM antenna" and guess what was one of the first results?

A test done on of all things....an FJR. How cool is that

Motorcycle Radio Antenna Comparison

https://www.webbikeworld.com/motorcycle-radio/antenna/

It may not be as detailed as you were looking for but should give you a good start.

Here is the Google result page if you want to check out some of the other resluts.

https://www.google.com/#sclient=psy-ab&hl=en&source=hp&q=motorcycle+FM+antenna&pbx=1&oq=motorcycle+FM+antenna&aq=f&aqi=g1&aql=&gs_sm=e&gs_upl=3206l11017l0l11495l21l21l0l9l9l0l390l2082l1.6.4.1l12l0&bav=on.2,or.r_gc.r_pw.&fp=b4f2a6b65f0a4e00&biw=1264&bih=720

Now I have a question.........

Did you install a radio and speakers on your bike and if so I would like to know more about your setup?

Right now I use a ScalaRider G4 and the FM works pretty good. But I always thought it would be fun to have a radio built in like you see on the big touring bikes.

EDIT: I think I just answered my own question when I came across this review done my a forum member and there is more antenna info in the review that may help you.

https://www.webbikeworld.com/motorcycle-radio/jensen-jhd910-radio/

Enjoy,

Jon...

The WebBikeWorld article probably has the best empirical info. I've got the 'hog tenna', which came with the Jensen radio I got from a forum member. I have it mounted on the inside of the right side panel. Its not the best solution, but it works well enough in the metro area for me.

There is always the fact that no matter how good the antenna, FM coverage in many non-metro areas is just crap. It might not be the antenna, but the fact that there ain't nuthin' out there to hear.

Now obviously, Slidell should have a fair amount of good radio. (By good, I mean usable signal, not program quality.) head north up into rural MS or west into Tejas and see what happens to FM reception.

Well, all I am going by is my comparison to any car that I have driven round here with an FM stereo. Always, without exception, I get a far better signal in the car. That makes me think I can do something to get better reception on the bike, but maybe not. I noticed in that review the guy said nothing about the lack of a ground plane. I am thinking of trying that small rectangular one that is actively amped. It's a crap-shoot!

Jon_PDX: No, I do not have speakers. I am using the Jensen radio and an Excort 8500 X50 radar detector mixed into an Ampli-Ryder mixer/amp, then into some Skull Candy ear buds. I frankly have no idea how thaose Harley guys can listen to the radio with external speakers when riding. Seems like you would hear just about nothing over 45 MPH.

Probably more than you were looking for but try this.

Well, I tried an in helmet solution about a year ago (I think I bought the Scala Rider). It was OK, but the FM reception was just about as bad as I have now, if not worse. That little antenna was not cutting it. And I had to use the in helmet speakers, so I did not have my noise isolation ear buds in. That meant I had to turn up the volume to hear. At 80 MPH on the interstate, I could not hear it much. I figured that was eventually going to damage my hearing so I sent the whole thing back.

I tried a couple different antennas with not much luck. The one that works best for me is a marine antenna that doesn't need to be grounded like this one linky.

I have it running from the radio up front, under the tank and the excess coiled up under the seat. It's cheap,invisible and does not pick up any interference from the engine. Still not as good as a car's antenna, but decent.

Thanks. What is 40" long, the antenna portion itself? You coiled that part under the seat, or were you talking about the coax portion? Thanks.

Woketman said:

Thanks. What is 40" long, the antenna portion itself? You coiled that part under the seat, or were you talking about the coax portion? Thanks.

Click to expand...

The coax just tapers down to a thinner cable and the cable itself is the antenna. There is no rigid whip or anything to mount. This picture shows it better: pic

That antenna makes it's own ground plane.

It works by using the center conductor as one element and the shielding of the coax as the ground. To put it another way, if you took a piece of coax and stripped off some of the outer shielding to expose the center conductor it would look like that antenna.

If a regular FM car antenna is 31" you would want to exposed 31" of the center conductor from a piece of coax. The advantage of mounting a 31" wip on a car vs on a motorcycle is there is more metal to act as a gound plane on the car. Yeah, yeah, we all already knew that

On the bike in the links I provided I think he uses a piece of metal to make a bracket for the antenna. The more metal the better but obviously there are limits to what you can do on a bike.

What would probably work pretty well would be to mount one of the short rubber car antennas on the top of the top box (trunk) and then line the inside of the lid to the top box with copper foil or something like that. Then run a standard car antenna lead (coax) from the radio to the antenna making sure the center conductor is attached to the antenna and the shielding of the coax is attached to the copper foil.

Lacking a trunk on the bike then a metal bracket attached to the bike would be the next step down.

With all that said, I just got off a 10 hour shift and am pretty tired and it's been awhile since I rattled off antenna stuff. So I may have missed a few things. But the electrical engineer at work you mentioned in the beginning should be able to help you come up with a mount that would work. If not, seek out a local Ham Radio person and for sure they should be able to get you fixed up.

Jon...