[PARC] Location of your mobile Antenna

[rpage]

Some will find this article interesting
Rick
ve3iqz


  Mobile Antenna Placement


    Best Placement of a Mobile Antenna


      Don’t Lopside Your Pattern!

Source: Larsen Amateur Catalog (PDF) 
<http://www.pulseelectronics.com/download/3598/larsen_amateur_catalog_/pdf> 
- Written by Aaron Logan.

We have provided you some guidelines for mobile antenna selection. When 
selecting a mobile antenna, there are a number of factors that 
significantly affect the ultimate performance of the antenna. Gain 
requirements, electrical type, ground plane availability mounting style 
and placement, coaxial type and loss ratings, physical size, appearance, 
and surrounding environment are all issues that must be addressed to 
ensure the maximum performance from a mobile antenna installation. The 
electrical type or design of the mobile antenna is commonly referred to 
in terms of its dimensions in terms of wavelength: 1/4 wave, 1/2 wave, 
5/8 wave, etc. Each electrical type has a specific radiating pattern to 
be considered when selecting a mobile antenna. For example, the signal 
radiating from a 1/4 wave antenna is directed more vertically, thus 
making it ideal in urban environments where buildings might obstruct the 
signal. The design of a 5dB collinear mobile antenna is designed to 
direct the signal more towards the horizon. This type of antenna is 
ideal for geographically flat regions where signal coverage is sparse.

antenna centered in roof of carGround plane availability is another 
critical factor in mobile antenna performance, and must be considered 
when determining the location and type of the antenna. Ground plane 
requirements vary given the type of mobile antenna and the frequency of 
operation. A typical 5/8 wave antenna at 150 MHz requires a ground plane 
of at least 42” in diameter. At 450 MHz, 15” is required, and 800 MHz, a 
minimum of 8” is considered sufficient.

In terms of mounting mobile antennas on a vehicle, there are five 
general locations: the roof, front fender, rear fender, trunk and rear 
window glass (although other glass mount locations may be used). Of 
these, the center of an automobile roof is considered the best for 
mobile antenna placement, followed by the center of the trunk lid, the 
fenders, and then on-glass mounting. This ranking is determined by the 
amount of ground plane provided by the positioning, and clearance from 
obstruction (i.e.: the roof line), and is the reason the center of the 
roof is considered the ideal mounting location, provided the roof is 
metal. The diagram above illustrates the effective loss (at 800 MHz) due 
to insufficient symmetrical ground plane.

2002: found at alfenterprises.com/AntennaIndexCategory.html (dead link); 
2015: located source in Larsonn Amateur Catalog; 2016: Author located! 
It is the policy of kv5r.com to properly credit all sources, when 
possible. This one just took a while!

 From the Author of the article:

Aaron Logan on January 2, 2016 at 1:05 PM 
<https://kv5r.com/ham-radio/mobile-antenna-placement/#comment-288> said:

Testing was completed at the Larsen Antenna manufacturing site in 
Vancouver, WA. This testing was done in an outdoor test field, multiple 
wavelengths from nearest buildings and structures in a controlled 
environment.

This information is directly from the Larsen catalog. (I wrote it while 
employed at Larsen – know Pulse Electronics.)

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