Directional Antennas

6/2/2021

This week we take a look at directional antennas.

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Digilent Analog Discovery 2 HRWB Bundle - https://store.digilentinc.com/ham-radio-workbench-bundle/
Coupon Code HamRadioWorkbench2021

PackTenna TrekMount portable VHF antenna http://www.packtenna.com

Lab599 TX-500: https://lab599.com

Portable: mcHF http://www.m0nka.co.uk/

Transverter va3mw was talking about https://www.ebay.com/itm/254510549922?hash=item3b4202cba2:g:k5UAAOSwAi9fFz6O

Flex radio WaveForms https://www.flexradio.com/documentation/smartsdr-waveform-api-pdf/

UHSDR on Github https://github.com/df8oe/UHSDR/wiki

Home: Flex 6400 https://www.flexradio.com/products/flex-6400-signature-series-sdr-transceiver/

Attended FDIM, won a SoftRock RXTX Ensemble! Not sure what to do with it… :-D http://fivedash.com/index.php?main_page=product_info&products_id=7

Morse tutor www.w8bh.net

Virtual ham band on the internet, V Band https://hamradio.solutions/vband/

MG Chemicals conductive paints https://www.mgchemicals.com/category/conductive-paint/

RS-485 magnetometer https://4o3a.com/azimuth-magnetic-sensor

20v Dewalt tool family https://www.dewalt.com/products/power-tools/shop-by-cordless-platform/20v

Antenna Theory Directivity

The National Film Board of Canada for the Canadian Air Forces - Great explanation of Directivity.
https://www.youtube.com/watch?v=ysNkjEnoRsU

Antenna Fundamentals Bandwidth. Military Training film.
https://www.youtube.com/watch?v=v6VE9xoA_6M&t=569s

Urban Beam: https://helpdesk.flexradio.com/hc/en-us/articles/202118688-How-to-Submit-a-Request-for-Technical-Support#:~:text=Just%20click%20on%20the%20Sign,of%20the%20HelpDesk%20home%20page
https://consumer.steppir.com/shop/horizontal-antennas/2-element-antenna-products/urbanbeam-package/

What ever happened to the quad? Used to be popular
https://www.electronics-notes.com/articles/antennas-propagation/cubical-quad-antenna/quad-basics.php

Smitty’s Comet H-422 https://www.cometantenna.com/wp-content/uploads/2013/09/H-422-instructions.pdf

Mark’s setup: https://youtu.be/Jd3iCfUe9H8

Doublet http://webclass.org/k5ijb/antennas/All-Band-Doublet.htm

9 Comments

David m0tfy

6/2/2021 18:48:44

Another great episode. Thanks

Mark N9TCA

6/3/2021 12:50:28

Great episode. As soon as I got home I have been anxiously looking through the web site for Vince's audio switching notes/schematic. Any chance that is coming soon?
Thanks
73

George

6/3/2021 13:24:18

Hi Mark, I just updated the HRWB web site. Look in the Articles section for Vince's pics and schematic.

Mark N9TCA

6/3/2021 13:37:08

Super, Thanks!

Steven AI5BH

6/4/2021 15:13:52

If you haven’t seen it yet, you can use QSOBot on the Morserino32 and have lovely QSOs with robots. You configure the WiFi peer, connect and send a qrl? It should respond with a k and then you can call CQ and start up a QSO with a virtual ham.

Mike Murphy link

6/14/2021 16:38:32

Hi guys! Allow me to make some comments on HRWB 130:

In my experience, having a yagi will allow you to hear 4 to 5 S units better than a vertical or a dipole. Just having something rotational really does make a big difference in receive.

On the topic of the Steppir antenna, boom length does impact the F/B on 10 meters according to Mike Mertel, K7IR at Steppir.

For a discussion about the Steppir boom length, please see: http://www.wp4sk.com/Home/equipment/steppir

The Steppir has several advantages that you did not discuss including reverse mode (allowing the antenna to make the director a reflector and the reflector a director). This allows you to electrically rotate the antenna without actually turning it. Also it has a bi-directional mode which would allow you to transmit in two directions 180 degrees apart.

Hex Beam - Buddipole will be releasing a portable version very soon. Jason from Ham Radio 2.0 has shown one on his channel a couple of times.

Quads are typically a 1 wavelength element (not a half wave like a dipole). They are also quieter on receive.

I knew someone who had a 4 element Gem quad a number of years ago. He also had a Yagi up as well. His comments comparing the two antennas were that the quad was better to open and close a band and also performed better in poor band conditions.

Also, if you have not seen one, look at the LFA yagi. (loop fed array) https://www.innovantennas.com/en/module-guide/lfa-yagi-benefits.html

Radio Arcala had a 160 meter beam and 80 meter beam on the same tower at one time before it was destroyed in a storm. It was a real monster. See https://www.youtube.com/watch?v=XCZcjqltJVA

Last thing, when you get to a show about feedlines, remember that loss is equal on transmit AND receive. I doubt most hams realize this.

Show length was perfect - Just enough time to mow and trim 3 acres!

- Mike - KI8R

Patrick Dell

7/9/2021 12:51:04

Just a small clarification on DC motors (2-wire brushed or 3-phase brushless) regarding a comment Mike made around 51:39 about lower voltage and "should be more torque" for the tower rotor... I offer a slight correction in mental model in the spirit of the amazing generosity your talented group provides to the community's collective lawn mowing experience.

Torque is directly proportional to current and has an aptly called torque or current constant (this is ignoring heating effects - Ohmic rise in the copper and the coefficient of magnetic remanence). The motor will consume no more current than the torque requires (load [friction, acceleration, and/or gravity] + [gear]motor's inherent friction). The available current is dictated by Ohm's Law: supply voltage divided by the sum of the winding resistance and brushes' (if present) resistance, so lowering the voltage typically lowers the possible* available torque (*limited by thermal dissipation and the limited capability of the magnetic circuit often provide a less than linear response curve above the rated current). For brushed motors, the viscous dampening constant (Eddy currents [Foucault currents], winding, etc.) is typically assumed negligible or nonexistent; however closed-frame brushless motors can often produce more torque at lower speeds as the heating losses related to the viscous dampening constant are lower.

If you would like to go into more depth, I would be honored to share with a such a talented and generous group. I truly appreciate what you give to the community.

Thank you,
patrick - N9RVI

Mark - K5YAC link

9/16/2022 03:40:42

Great topic!

Lots of quad antennas in use from HF thru UHF. A quad is not a yagi made into a full wave loop, it IS a full wave loop… the yagi is not. HF quads are still Kings of DX and many are on the air. Lots of 6, 8 and 10-element VHF/UHF models are used for local and satellite work, and phased arrays are common for EME. As for the comparison to the hexbeam, the only similarity is that they are both wire antennas. A 2-element quad will far outperform a hexbeam (I have tested both) and the quad has a smaller turn radius with only slightly higher wind load. Quiet on the noise and big on gain!

Mark - K5YAC link

9/16/2022 03:43:53

Also, I heard the words “log periodic” mentioned, but no one picked up to comment further. Another fantastic design. While there is some trade-off when comparing to a yagi of similar size, the major benefit is broadband capability on a single feedline. Sure, the gain is not quite what you may find with a mono-band yagi, but the ability to spin the dial from 13-30MHz without the need for a tuner is nice. F/B ratio and rear/side rejection ranks well too.

Fun topic, I hope you will discuss again.

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Directional Antennas

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