[OFARC] portable HF antenna questions

[Mark]

https://www.tmastco.com/main/page_products_telescopic_poles.html

 

Keep it simple.  Wire to the top and random wire tuner or loading coil at
base. 

 

Hamstick on a tripod. Cheap, simple.

 

http://alphaantenna.com/index.php?main_page=product_info
<http://alphaantenna.com/index.php?main_page=product_info&cPath=17&products_
id=85> &cPath=17&products_id=85

 

The Alpha antennas work pretty good.  Jim McClain has one. 

 

http://www.buddipole.com/buddistick.html

 

Pricey but good quality

 

 

 

 

From: ofarc-bounces at mailman.qth.net [mailto:ofarc-bounces at mailman.qth.net]
On Behalf Of Ralph (home)
Sent: Tuesday, March 20, 2018 11:58 AM
To: OFARC; Herb Phillips
Subject: [OFARC] portable HF antenna questions

 

I have been looking at possible designs for a portable HF antenna, but am
having some questions.

My goal is to have something that can be put up in an open field or parking
lot where there are no trees or other supports available.

The radiating element should be at least 6 ft above grade to minimize
contact by people or animals.

 

I am leaning toward using a vertical section to support an inverted V

A 20ft vertical support and a guy radius of 10 ft will make a 20m inverted V

30 ft vertical and 25ft guy radius will give me a 40m V

 

Will metal pipe used to support an inverted V cause major changes to the
tuning or radiation pattern?

 

Any advice is welcome on these designs or something else.

 

Ralph

KE5HDF

 

 

Possible designs

                ½ wave vertical fed at bottom + 3 or 4  ground wires+ tuner
at feed point (20 m = 32.8 ft)

                ¼ wave vertical fed at bottom + ground wires + tuner at feed
point (20m = 16ft, 40m=33 ft)

                ½ wave vertical dipole fed at center  (20m = 32.8 ft + 6ft
above ground )

                ½ wave Inverted V fed at top (20m or 40m)

 

I could make the vertical antennas from:

wire supported by PVC (conduit, swaged at one end)

sections of light weight metal tubing (chain link fence top rail, swaged at
one end)

Plastic pipe will likely flex/sway more than metal but is cheaper

 

I could make a vertical support for the inverted V from the same materials.

Either way, the vertical pipe would be held up by guy lines and base plate

 

>From my research on-line and in some books, it appears that only the
inverted V and vertical dipole will give impedance anywhere near 50 ohm.  A
match of some sort will be needed, even if a tuner is used.

It appears the vertical dipole and inverted V have better radiation patterns
and gain thank the monopoles

 

 

 

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/ofarc/attachments/20180324/29c5a7d6/attachment.html>