Saturday, November 17, 2012

"Balanced Line" Franklin Collinear Arrays

"Balanced Line" Franklin Collinear Arrays

The Franklin Array exhibits good gain (~4.5 Db), and delivers better than average signals, even when hung at only a quarter wavelength (low). This is possible since the array has no vertical component or vertical directivity, while capture area, and horizontal directivity and gain increase substantially with the 4-element collinear configuration. The MFJ-64xx arrays use fully balanced tuners (MFJ-974H, MFJ-974, and MFJ-971 series) to apply power to the array, and match the system to coax input. Figure 1 illustrates a Franklin Array.
Dimension "L1" represents a ½ wave, "L2" represents slightly less than ½ wave, and "F" a ¼ wave, which, in this case is a ¼ wave stub, used for phase-shifting. The antenna is a "broadside array," and is bi-directional perpendicular to the run of the wire.
A pair of these antennas at right angles (NE/SW; NW/SE for example) can provide world-wide coverage when used with a suitable antenna switching system. The added gain means your array presents an effective power gain of "3". This means 100 watts applied results in the effective radiated power of ~300 watts! What if you apply 1500 watts out? Pretty good results for "hanging wire!"
If height is a constraint, this antenna functions better than average at even a bit less than a ¼ wavelength above ground/structure. However, it really performs best if "hung" at a ¼ to ½ wave; up to ¾ wave. Higher than that provides diminishing return. Once fully balanced tuned, you'll find the antenna presents a low SWR across the entire band. However, it is a "one-band antenna" functioning as a Franklin Array; other bands provide varying patterns when tuned and matched.
Especially important is keeping the symmetry of the antenna in reference to its ½ wave radiators. They must not sag more than a foot or so, with pulled-tight being the best installation. The feedline/stub can be "bent" at the bottom, or pulled away at an angle, and some twisting is OK. Practically, it is best to let the stubs/feeder hang straight down and tie them off with rope to avoid lashing about in windy conditions.
Figure 1
Franklin Array (Four Half-Waves Collinear/In-Phase)
To summarize, these antennas are intended for single-band use (your favorite):
  • 15 meters (92 feet long; 12 feet high)
  • 17 meters (108 feet long; 13.5 feet high)
  • 20 meters (136 feet long; 16 feet high)
They require two tie-off points spaced far enough to accomodate their width and length, and a height at least close to ¼ wavelength. Note that these arrays "hang and play" in about same distance taken by an 80 meter doublet. When using two antennas, try to locate the antennas in an "L" or "T" ("X") configuration (at right angles) as illustrated in Figure 2.
(Looking Down From Above)
Figure 2
Two Antennas @ Right Angles (Suggested Optimum)
We hope you will benefit from their ease of installation, efficiency, and quality construction.


Madhu Bala said...

This is my first visit to your blog, keep writing more content.

French Classes in Chennai
Big Data Training in Chennai
Android Training in Chennai
Selenium Training in Chennai
JAVA Training in Chennai
German Classes in chennai
java training in tambaram

Pathway for German Language said...
This comment has been removed by the author.
Syahy's Blogger said...

This is additionally a generally excellent post which I truly delighted in perusing. It isn't each day that I have the likelihood to see something like this.. data science course in chennai

Turkey visa for US citizens said...

Keep up the work, great job! The Turkish government has introduced an online visa system that allows US citizens to obtain a visit visa electronically. Turkey visa for US citizens , US citizens can now easily apply for Turkey Visa from their home or office.

kenya evisa cost said...

Nice post. Thank you for this work. The travelers need to apply visa for Kenya through online visa application. Check the details and read the guidelines before you fill up the application form and pay kenya evisa cost.

India e visa cost said...

I love to read this, thank you...India e visa cost , You can check visa fee online via Evisa-Indian portal, And visa fee depends on your nationality.

Ava said...

This article is really very helpful for me and I really appreciate you for sharing it with me… Emergency / emergency Indian visa application form (Process within 1 to 3 days) You can easily avail the facility for immediate processing of your Indian Visa by applying through the fast track Indian visa services we provide.

Lorriel Sims said...

This shield is connected to ground like unbalanced lines but it is not required as one of the signal conductors at building a casita in las vegas

kit roymond said...

I am enjoying every bit of it. It is a good site, as well as the stock is well-chosen. Thank you India electronic business visa, you can get an online India business e visa through the India e visa website. India e business visa is more convenient and hassle-free.

Nathan said...

Great article! It's really useful and informative. With the new updates, it's very innovative and interesting. Thanks. Travelers have the question: can US citizen travel to India? The answer is yes. it is now easier than ever to get an Indian visa. The whole immigration process can now be completed online.

dennishcaraid said...

I really love to read such an excellent article. Helpful article. Do you know you can get an India e tourist visa now? Yes, It is again possible to travel to India with a tourist visa. You can apply for the required tourist visa to India with the online application form. You will then receive the visa by email. It allows you to travel to India.

Lucas mia said...

I am really thankful to the owner of this web page who has shared this wonderful writing at this place.Do you know Digital marketing strategy & types of digital marketing? No, If you have any query related to Digital marketing services then visit our website will get complete information related to your query.

Edison Berg said...

Hello guys, many people ask, how can I apply for a visa? You can e visa apply online. And your visa processing time depends on your nationality and your visa type.

Anonymous said...

Nice site. Keep up the great work Securities Fraud Case Studies