Thread: 4NEC2?
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Old October 15th 18, 02:20 AM posted to uk.radio.amateur,rec.radio.amateur.antenna
Jeff Liebermann[_2_] Jeff Liebermann[_2_] is offline
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First recorded activity by RadioBanter: Jun 2007
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Default 4NEC2?

On Sun, 14 Oct 2018 11:12:14 -0700, Jeff Liebermann
wrote:
(...)
However, if you plan to do more than that, some test equipment might
be useful.


Since you prefer a minimalist approach to test equipment, as an
alternative to your light bulb, may I suggest a return loss bridge:
https://www.google.com/search?q=return+loss+bridge&tbm=isch
Note that there are several basic designs and configurations but all
are fairly simple and easy to construct. Note that these are NOT the
same as directional couplers.

You can purchase them on eBay:
https://www.ebay.com/sch/i.html?_nkw=return+loss+bridge

There are tutorials on YouTube:
https://www.youtube.com/results?search_query=return+loss+bridge

I have three of these made by Texscan:
https://www.qsl.net/n9zia/wireless/rtrn_loss-pics.html
https://www.qsl.net/n9zia/rlb/texscan.png

and a few that I've built for microwave frequencies:
http://pe2er.nl/wifiswr/

and one for HF:
http://www.dicks-website.eu/return%20loss%20bridge_part1/part1.html
http://www.dicks-website.eu/return%20loss%20bridge_part2/part2.html
http://www.dicks-website.eu/return%20loss%20bridge_part2/part3.html
http://www.dicks-website.eu/return%20loss%20bridge_part2/part4.html
http://www.dicks-website.eu/return%20loss%20bridge_part5/part5.html

A return loss bridge is similar to a VNA except that it does not
produce numbers for the real (resistive) and imaginary (reactive)
components of the antenna impedance. It just produces the return loss
compared to a reference termination resistor, which can then be
translated into the VSWR.

To use it, you need a minimum of an RF signal generator and a
voltmeter or oscilloscope. I prefer to sweep the frequency range of
interest, so I use an RF sweep generator, and display the result on an
oscilloscope. With this arrangement, you can tune your antenna
without requiring a light bulb.


--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558