Menu

5/8 wave ground plane

Search this Thread

Prev

Previous Post

Next Post

Next

#20

Report Post

Old

May 18th 04, 04:17 PM

Dan Richardson

Posts: n/a

Default

On 18 May 2004 06:19:50 -0700, (Brian Kelly) wrote:

Then howcum my 5/8 wave mag mount 2m mobile antenna very significantly
outperforms the 1/4 wave mag mount antenna I used to use? Same ground
condx, same power, same feeder length, same vehicle, etc. I suspect
it's in the differences in the TO angles.

My previous response was for a ground plan antenna mounted above
ground and you are addressing a mobile installation. They are
different.

I've done modeling of 1/4,1/2 and 5/8-wave whips using several wire
grid models for vehicles (small and mid-sized car, small pickup truck
and a SUV). I found that the vehicle's size, shape and whip location
plays a major part in performance.

I also noted, on the average, the 5/8 produce a slight gain over all,
but it was possible to find azimuth directions that a 5/8-wave would
produced almost 3 db gain over itself - depending what vehicle it was
mounted on.

The most outstanding feature I saw was a 5/8-wave whip azimuth pattern
was less influenced by the vehicle geometry.

The operation is more like a lop-sided dipole with the vehicle body
being on leg.

I don't feel you can accurately predict how a the whips will perform
on a vehicle based upon operation on another vehicle - unless both
vehicles and the antenna locations are the same.

I should add for all models the whips where placed top-dead-center of
the vehicle's roof.

73,
Danny, K6MHE

Reply With Quote

Reply With Quote

Thread Tools	Search this Thread
Show Printable Version	Search this Thread: Advanced Search
Display Modes
Switch to Linear Mode Switch to Hybrid Mode Threaded Mode

Posting Rules
Smilies are On [IMG] code is On HTML code is Off Trackbacks are On Pingbacks are On Refbacks are On

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Inverted ground plane antenna: compared with normal GP and low dipole.	Serge Stroobandt, ON4BAA	Antenna	8	February 24th 11 11:22 PM
Plans for a 5/8 wave 2M ground plane	George Cronk	Antenna	21	April 6th 04 11:14 AM
QST Article: An Easy to Build, Dual-Band Collinear Antenna	Serge Stroobandt, ON4BAA	Antenna	12	October 16th 03 08:44 PM

All times are GMT +1. The time now is 02:30 PM.

About Us

"It's about Radio"

Contact Us RadioBanter forum home Privacy Statement

Copyright © 2017