Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: LOOKING TO MAKE AN EASILY DEPLOYABLE PORTABLE ANTENNA FOR 20, 40 METERS  (Read 938 times)
KB1IUI
Member

Posts: 48




Ignore
« on: January 08, 2013, 04:43:03 PM »

Looking for some plans to make an easily deployable antenna for 20 and 40 meters. Something I can put up quick for demonstrating ham radio to children. Trees are usually available. I have a limited range ATU in my Yaseu 450D(that I am still figuring out how to use). Could something as simple a a dipole still work well on both bands? This is my first real venture into HF as I use to be on 2m only.

Mike
KB1IUI
Logged
WB6BYU
Member

Posts: 12986




Ignore
« Reply #1 on: January 08, 2013, 05:08:52 PM »

There are lots of possibilities.  My favorite is a simple dipole, because it is versatile
and  can fit in many situations.  Typically I cut dipole wires for each band, and each
time I set up I attach the wires for the bands I want to use to the center insulator
on the end of my coax.  For backpacking I use 25' of RG-174, or 50' of RG-58 when
weight and space aren't a concern.  I can set up for 1 band or 80/40/20/15/10m as
conditions permit.  My backpacking dipoles have operated from VE1/KL7/KH6/ZL/VK
as well as at least 7 mainland states.  I tuned them up initially in a park, and don't
bother to carry an antenna tuner in my backpack (except for special occasions.)

Other options would include a trap dipole or other ways to make it resonant
on two bands, G5RV (regular or half-size) or ZS6BKW antenna, end-fed wires with
fixed tuners, random wires, vertical whips, etc.  I've used loops, vee-beams, long
wires, quads, and other sorts of wire arrays when operating portable, but the dipole
is my first choice for simplicity and ease of installation.  If I don't know what I'm
going to encounter, I always bring along a dipole.
Logged
W5DXP
Member

Posts: 3532


WWW

Ignore
« Reply #2 on: January 09, 2013, 05:16:24 AM »

Looking for some plans to make an easily deployable antenna for 20 and 40 meters.

If you have trees, a ZS6BKW may be a good choice. That's about 92' of dipole fed with about 40' of ladder-line, "450" ohm preferred but 300 ohm will work. Bonus is that it also works on 17m, 12m, and 10m. Feed it through a 1:1 choke on the ladder-line. Often doesn't require a tuner.
Logged

73, Cecil, www.w5dxp.com
The purpose of an antenna tuner is to increase the current through the radiation resistance at the antenna to the maximum available magnitude resulting in a radiated power of I2(RRAD) from the antenna.
AD5X
Member

Posts: 1426




Ignore
« Reply #3 on: January 09, 2013, 06:32:00 AM »

Build a 40M dipole with switches at the halfway points to disconnect half the antenna elements so it can resonate on 20M when desired.  If you don't have space for the full 40M length, build a 20M dipole with switches at the half way point and hang loading coils across the open switches to make it work on 40M.  See the "Portable Dipole" article in the "Articles" section of my website at www.ad5x.com.

Phil - AD5X
Logged
WB6BYU
Member

Posts: 12986




Ignore
« Reply #4 on: January 09, 2013, 08:57:21 AM »

Quote from: AD5X
Build a 40M dipole with switches at the halfway points to disconnect half the antenna elements so it can resonate on 20M when desired...


I've done the same thing, but using color-coded Anderson connectors in place of the
switches.  So the ARES 40/80/160m dipole has one junction in the middle of each side,
that is open for 40m, closed for 80m, and jumpered with a loading coil for 160m.  The
instructions then say, "For 80m connect the green and yellow plugs", which makes it
easier for untrained operators to set it up.  The 160m loading coil also has mating
connectors so it just plugs in.


That brings us back to a question about your original requirements:  do you want to
be able to work both bands without having to change the antenna?  If you switch
back and forth a lot, you'll probably want an antenna that handles both at the same
time, otherwise an antenna that can be switched between bands will work.
Logged
K5UNX
Member

Posts: 219


WWW

Ignore
« Reply #5 on: January 09, 2013, 09:22:37 AM »

Just to throw out another option, I am going to build a "buddistick". The instructions are https://sites.google.com/site/w3ffhomepage/.

I know it may not be as good as a dipole, but I'll eventually build one or more of those as well.
Logged

AE5JU
Member

Posts: 223




Ignore
« Reply #6 on: January 09, 2013, 01:32:31 PM »

Let me highly recommend a 66' overall length OCFD (aka "Windom").  4:1 Current Balun, 44' one side, 22' on the other.  Will work 40-20-10.  Will not work 15 meters no matter how good  your tuner, but hey, that's OK. 

Feed it with 50' of RG8X

We use one for some of our special event stations in parks, etc.

Some parachute cord to tie up the ends, pulled over limbs by first casting (with fly rod) a fishing weight, pull up the paracord on the ends.

Paul - AE5JU
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!