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Search: Posts Made By: GroundUrMast
Forum: FM Fool Discussion/Database Updates 24-Jan-2012, 7:47 AM
Replies: 29
Views: 33,607
Posted By GroundUrMast
Theoretically, the fundamental idea is...

Theoretically, the fundamental idea is workable... but like an any other mobile radio, you'll usually want an antenna that's omnidirectional. The bi-quad you've linked to is a uni-directional...
Forum: FM Fool Discussion/Database Updates 20-Jan-2012, 9:22 PM
Replies: 29
Views: 33,607
Posted By GroundUrMast
Sorry about that, I offer the modeling software...

Sorry about that, I offer the modeling software code for any who may be interested in it. I hope the attached graphics may be helpful in visualizing the changes to the radiation/receiving pattern as...
Forum: FM Fool Discussion/Database Updates 19-Jan-2012, 7:16 AM
Replies: 29
Views: 33,607
Posted By GroundUrMast
Comparison of 1/4 vs 5/8 radiation patterns

Here is a 3D model view of the radiation patterns of the common 1/4 wave whip compared to the theoretical radiation pattern of a 5/8 wavelength base loaded whip.

Both are simulated over perfect...
Forum: FM Fool Discussion/Database Updates 18-Jan-2012, 7:45 AM
Replies: 29
Views: 33,607
Posted By GroundUrMast
As I suspected, the "antenna" shown on Youtube...

As I suspected, the "antenna" shown on Youtube and in the drawing has extremely high SWR (in excess of 2000:1) in the FM broadcast band which means it will simply reflect almost all of the signal...
Forum: FM Fool Discussion/Database Updates 18-Jan-2012, 7:41 AM
Replies: 29
Views: 33,607
Posted By GroundUrMast
4NEC2 model of YouTube semi-fractal

CM
CE
SY WR=#16
SY DEX=0
SY PLS=0.0254
SY DESEGL=0.0254
SY DEPCGZ=0.1016
GW 1 5 DEX PLS/2 DEPCGZ/2 DEX (PLS/2)+cos(30)*DESEGL (DEPCGZ/2)+sin(30)*DESEGL WR...
Forum: FM Fool Discussion/Database Updates 18-Jan-2012, 3:57 AM
Replies: 29
Views: 33,607
Posted By GroundUrMast
If I can find time in the next few days, I'll...

If I can find time in the next few days, I'll model the drawing in 4NEC2. I'll have to estimate some dimensions since they're not provided.

Without modeling anything though, this looks like a UHF...
Forum: FM Fool Discussion/Database Updates 17-Jan-2012, 6:47 AM
Replies: 29
Views: 33,607
Posted By GroundUrMast
For a vehicle in motion or frequently moved then...

For a vehicle in motion or frequently moved then parked in various locations and facing a random direction, you'll need an antenna that has fairly equal reception from all directions.

As I...
Forum: FM Fool Discussion/Database Updates 11-Jan-2012, 4:12 AM
Replies: 29
Views: 33,607
Posted By GroundUrMast
With a well tuned, custom built collinear, you...

With a well tuned, custom built collinear, you would be doing quite well if you achieved 6 dB gain compared to the stock antenna. That would theoretically let you receive the same signal strength at...
Forum: FM Fool Discussion/Database Updates 8-Jan-2012, 6:15 PM
Replies: 29
Views: 33,607
Posted By GroundUrMast
100 MHz is right... or certainly close enough. ...

100 MHz is right... or certainly close enough.

A vertical antenna with gain is going to be larger than a 1/4 wave whip mounted on a fender.

Then you'll need to consider impedance matching...
...
Forum: FM Fool Discussion/Database Updates 8-Jan-2012, 4:56 PM
Replies: 29
Views: 33,607
Posted By GroundUrMast
https://www.google.com/search?hl=en&site=&q=5+8+an...

https://www.google.com/search?hl=en&site=&q=5+8+antenna+calculator&oq=5%2F8+ante&aq=0&aqi=g3g-v5g-j2&aql=&gs_sm=c&gs_upl=2188l6774l0l9297l8l8l0l0l0l0l284l1477l0.6.2l8l0
...
Forum: FM Fool Discussion/Database Updates 8-Jan-2012, 2:41 AM
Replies: 29
Views: 33,607
Posted By GroundUrMast
For FM reception in motion, the stock 'whip'...

For FM reception in motion, the stock 'whip' antenna on most vehicles is at or near resonance and is a very good antenna for the application. In theory you could look at 5/8th wave and collinear...
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