REALIZED ANTENNA PROJECTS 

2m and 70cm hentenna (2013)

Also hosted by HamUniverse.com (section #3, category HF Experimental)




20/17/15/12/10m circular magnetic loop (2012)
and a comparison with a little one for the 2m band





 20m EH antenna by F5SWN (2011) 

The EH antenna, patented by Ted Hart W5QJR (link to patent), is still today the subject of discussion since the beginning of the new millennium (link to official page).
Many physicists, engineers and amateur radio operators have investigated about its properties, using different approaches and tools.
The Poynting Vector Synthesis (PVS) theory at the basis of the EH antenna working principle seem not to be survived to any scientific investigations (read I1RFQ's paper).
Probably the answer about the mistery of this antenna is not to inquire into some new e.m. theory but just in the common mode current flowing on the shield of the coaxial cables that will radiate.
It's not my intention to approach a new discussion about this dilemma, I just want to share with you my experimental personal contributor, in order to provide some useful data about the performance of this very short antenna (respect to the wavelenght of the resonance frequency).
To reach this goal, I've realized an exemplar of the F5SWN version (see here).
I've measured the same characteristics in terms of SWR and bandwidth, using both 20m (the same wavelenght of 14MHz) of RG58/U coax cable and a lenght of just 3.5m long one.
Follow a picture of the SWR-meter, virtual instrument built inside my IC-7000, showing a bandwidth of 130KHz centered on 14.230MHz (each bar is 10KHz wide) with an SWR < 1.4:1 (under the red limit):

SWR diagram of the 20m F5SWN EH antenna

Using max 100W and my IC-7000 rig, from inside my QTH (locator JN63RH) I've estabilished the following QSO (you can see the details in my QRZ.com logbook):

Date
Power [W]
Mode     
Remote station's call
 
QTH
RST SENTRST RX
19-02-2012 100 SSB 
ON4LT
  
Belgium ---- 
25-03-2012100 SSB  
EA5DFV
 
 Spain 
55
-- 
02-09-2012 -SSB  
7T50I  (
just rx)
Algery 
59
-- 
02-09-201240SSB 
MM0AOQ
 
 Scotland
57 
59
 
02-09-201240SSB 
G6YB
 
U.K. 
59
  
-- 
02-09-201275SSB 
G3BKF
 
U.K.
59 
59
  
30-03-201350SSB F4KJBFFrance
59+20
59+10
  
31-03-201350 SSB LZ5X Bulgaria  
59+10 
59+10
 
31-03-201350 SSB ES9C Estonia 
59 
 
59
 
01-04-201350  SSB LZ2LP Bulgaria  
59+20
59+20
 
16-04-2013SSB  
N4LEM  (
just rx)
 
USA
59+10
 
 -- 
21-04-2013 20SSB 7S55SEngland 
59
56 (*)
 
21-04-201350 SSB GB2VEFEngland 
59
55
 
21-04-2013 10 SSB OZ/PA7PA  Netherlands 
59
59
 
30-04-2013   50  PSK31 US7KC Ukraine 
599
 
 
579
14-09-201380 SSB CK3AT   Canada
59
 
59 (contest)
27-10-2013 100SSB  BA7JA  China
59
 
 
59 (contest)
 
(*) 
replacing the EH antenna with a 1m diameter magnetic loop, in the same operating conditions,
I've received RST 57 (+1 point) and I've sent RST 59+10 (+10dB).

I have detected the following phenomena:
- the tuning is strongly dependent on the path and the lenght of the cable
- the tuning depend on the antenna height from the ground (still works well on the floor and rising it increases the tuning frequency)
- the cable seems radiating: some feedback into the radio sometimes appears increasing the power... if the cable pass too near my IC-7000, its display flickers and also a band and mode switching has appeared...
- using the short cable, the noise increases up to signal 9/9+10
    -

       
Finally, this is my 20m antenna!



        
 40m EH antenna by F5SWN (2012) 

In the wake of the enthusiasm arising from the experiments conducted with the EH for the 20m band, I'm newly here to present some data collected with the 40m version:

Date
Power [W]
Mode   
Remote station's call
 
QTH
RST SENTRST RX
31-03-2012 50SSB DR1AGermany5559


As for the 20m "sister", I've captured a screen of the SWR-meter built inside my IC-7000, showing a bandwidth of 130KHz centered on 7.130MHz (each bar is 10KHz wide) with an SWR < 1.4:1 (under the red limit):

SW

the BW results a little narrower than the 20m version.

The two "sisters"
20m and 40m EH antennas



I have detected the following phenomena:
- I confirm all that I've detected  experimenting with the 20m version of this antenna, using both 20m and 3.5m of RG58/U coax cable
- Signal are worst respect to the 20m version
- The noise is very high in the 40m band (silence at S9) but unlike the 20m version that receives signals only in its resonance band, this bigger antenna receives very well signals both in the  20m and 80m bands! Very clear signals up to S5.

Conclusion

Compared to a magnetic loop antenna these performance are surely scarce, but I hope that my work could be useful to everyone that have the desire to build and experiment with this kind of antenna.
For example I suggest to compare the performance of the classic version with the F5SWN that I've built and presented.
I hope to listen to you on-air!!!

                                                              73 de IW6DFW, Maurizio




DISCLAIMER: All contents are only intended for educational, experimental and demonstrative purpose, so I decline
any kind of responsibility regarding every possible problem consequent from their use.