[Hackrf-dev] Antennas, Cables and Connectors [Important Questions on RF Performance]

Thu Sep 4 08:16:34 EDT 2014

Hello Everyone,

I just received my HackRF this Tuesday. As I had not ordered it under the
Prototype category on KickStarter I did not receive the Antennas that Mike
was sending out. Before I received my HackRF I wanted to get all the
necessary cables, connectors and antennas that I would need to use with the
HackRF.

Disclaimer: I am adding links for items I have purchased so it’s easier for
others to look up the specs and if they wish, order the parts. I am in no
way affiliated with any supplier mentioned below and this is not a
marketing attempt. I do not endorse any of the products mentioned below.

The following is a list of items I have purchased along with the sources
and spec sheets for each. I compiled this list of items based on posts by
Mike on Kickstarter and searching for some stuff myself
https://www.kickstarter.com/projects/mossmann/hackrf-an-open-source-sdr-platform/posts/758974

Items:

1)     1) ANT 500

2)     2) Log Periodic Antenna covering frequencies from 850 MHz to 6500 MHz
- http://www.wa5vjb.com/pcb-pdfs/LP8565.pdf

3)     3) Danets Yagi Antenna comes with WiFi Dongle connected -
http://amzn.com/B003LLS5JI [Not designed to be specifically used with
HackRF though can be modified (though not advised) to use with HackRF]

4)    4)  Another Yagi Antenna for 2.4GHZ spectrum from China – Don’t have
the link or specs for this one

5)    5)  CONNECTOR,RF,SMA,JACK TO JACK,.STRAIGHT,GOLD PLATED -
https://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=153294

Spec Sheet: https://www.jameco.com/Jameco/Products/ProdDS/153294.pdf

*6)     *Cable Assembly SMA Male to SMA Male 6 Inch RG-174 Coax Cable 50
Ohm -
https://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=169801

Spec Sheet: https://www.jameco.com/Jameco/Products/ProdDS/169801.pdf

*7)     *Cable Assembly SMA Male to SMA Male 2 Foot RG-174 Coax Cable 50
Ohm -
https://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=153382

Spec Sheet: https://www.jameco.com/Jameco/Products/ProdDS/153382.pdf

*8)     **Connector SMA Female Solder Right Angle Thru-Hole Gold – *

*https://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=145374
<https://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=145374>
*

*Spec Sheet: https://www.jameco.com/Jameco/Products/ProdDS/145374.pdf
<https://www.jameco.com/Jameco/Products/ProdDS/145374.pdf>*

Notes: You need this Connector be able to use the Log Periodic Antenna as
it does not come with any connector. The Connector needs to be soldered on.
You can use other connectors but I decided to go with SMA as Mike chose
them for the HackRF one. He made the switch from RP-SMA in the Jawbreaker
to SMA because he felt they were better. I trust his choice, hence decided
to go with SMA.

*9)     *Connector SMA Receptacle 0Hz to 18GHz 50Ohm Solder Straight
Thru-Hole Gold -
https://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=145382

Spec Sheet: *https://www.jameco.com/Jameco/Products/ProdDS/145382.pdf
<https://www.jameco.com/Jameco/Products/ProdDS/145382.pdf>*
Notes: You need this Connector be able to use the Log Periodic Antenna as
it does not come with any connector. The Connector needs to be soldered on.
You can use other connectors but I decided to go with SMA as Mike chose
them for the HackRF one. He made the switch from RP-SMA in the Jawbreaker
to SMA because he felt they were better. I trust his choice, hence decided
to go with SMA.

*10)  *Connector SMA Adapter M/M Straight Gold -
https://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=161294

Spec Sheet: *https://www.jameco.com/Jameco/Products/ProdDS/161294.pdf
<https://www.jameco.com/Jameco/Products/ProdDS/161294.pdf>*
*      11) SMA Male to SMA-RP Female Adapter - *http://amzn.com/B005H488Y4

I am not an RF engineer. I have been studying for my HAM exam this summer
and based on the study material and what I have read I made the best
judgment on purchasing these products. It is my understanding and please
correct me if I am wrong that RF enthusiasts spend a good deal of money on
Antennas, Connectors and Cables as these are as important as the equipment
receiving and processing the signals.

I have some questions for the HackRF Community and any Radio Engineers that
maybe on this forum:

Q1. Is there any difference between using item 8 and 9 on this list with
the LPA Antenna. I ask this because I don't know much about Harmonics and
this maybe something that I am confused about and have gotten totally
wrong, but will using the Right Angled Connector as opposed to the straight
connector make a difference in being able to use the HackRF on certain
higher frequencies as mentioned in the SDR Tricks with the HackRF talk by
Mike at DefCon https://www.youtube.com/watch?v=4Lgdtr7ylNY [Jump To 20:10
to see what I am talking about]. Mike was there any particular reason you
used the straight connector for your prototype backers as opposed to the
right angled one? See
https://www.kickstarter.com/projects/mossmann/hackrf-an-open-source-sdr-platform/posts/758974
I
have never used the LPA so I am not sure how it should be held to get the
best signal and I would like to know if it would be better to use one
connector over the other? Would like to learn from other's experience.

Q2. I also wanted to know if these products are high quality products based
on the spec sheets I provided or if I should have purchased something else,
specifically as far as these connectors and cables go.

Q3. I am planning on using Item#10 with Item#5 in series with the HackRF.
So to Visualize--->  [HackRF>SMA Male to Male> SMA Female to Female>
Whatever Antenna]

I want to use this configuration as a sacrificial connector as mentioned by
Mike in
https://www.kickstarter.com/projects/mossmann/hackrf-an-open-source-sdr-platform/posts/758974#comments
so as to extend the life of the SMA Female Connector on the HackRF over 500
cycles(Mike mentioned you can get well over 500 cycles but this just
increases the life even more). Will this create too much loss of signal?
Note these are gold connectors. Is the signal degradation small enough to
justify the use of these sacrificial connectors?

Q4. I see some of the Antenna manufacturers creating these graphs of signal
strength over frequency as seen in the Spec sheet for the LPA
http://www.wa5vjb.com/pcb-pdfs/LP8565.pdf on page 2 and even in Mike's
Presentation https://www.youtube.com/watch?v=4Lgdtr7ylNY Jump to [20:10] Is
there a reliable way across different software platforms to create these
graphs. I would really like to test the RF performance of the HackRF with
different combinations of these connectors, cables and antennas. Mike would
you consider making a video that shows us how to do that. This can be
useful to the community as we can vet connectors, cables and antennas for
performance. There are so many different versions of each available from so
many different vendors that it is very difficult to weed out the bad ones.
This will make it easier for everyone to calibrate and test our antennas
and I am sure we will all learn something in the process.

Q5. Mike this is an impressive graphic though from a different project
https://www.kickstarter.com/projects/1085541682/bladerf-usb-30-software-defined-radio/posts/491106
would
you cover something similar to help demystify the use and creation of such
graphs to help us understand Radio and calibration of our devices better?
Thanks.

Okay this has been a very long post and I have asked a lot of questions. I
thank you for your patience and will appreciate any feedback.

-- 

Sohil Shah.

Nothing is Impossible, Never Undermine the Potential of the Human Spirit =
My Life's Motto!!
Stay Hungry, Stay Foolish - Steve Jobs
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://nine.pairlist.net/pipermail/hackrf-dev/attachments/20140904/9d66f5c9/attachment.html>