Update on portable HF vertical antenna (40-10m)

Couple of days ago I had posted a writeup on my trial AHVD antenna. While it seems very clean design, to get efficiency out of such asymmetric dipole requires careful adjustment of vertical element vs radials (asymmetric ratio). Elevated legs gives it further boost due to decoupling effects from lossy ground. It would have been nice to have properly marked telescopic Aluminum tubing to go for short trips. However, unavailability of such fine tubes here, drove me to assemble wires and mash them with Aluminum L angles, center boards, wires, nuts n bolts etc. I thought this is bit too much for my operations. What else I can do if have to cut down on poles required, remain stealthy and light weight?. 

Circling back to the basics, Why not ground mounted vertical with few(8 to 12) short ground radials?. I may lose bit of efficiency, but hey, anyways, I am not going to place this antenna on a poor ground for serious contests or DX operation. So, quickly turned the AHVD to simple vertical system with same Prolite tripod stand and single 5m Caperlan fishing rod.  Tripod was just at 4ft level where the central connector went in. I placed air core coil which was designed for 40m AHVD through the base of Caperlan rod. I removed base plastic cap of fishing rod and pushed it over the top of Tripod mast (with some rubber pad inside for cushioning) for around 6-8inches. I used around 4.5meters of wire to go vertical and 6 random length (4 to 5 meter long) of wires on the ground. Beauty of the system is that, I can quickly adjust the length of vertical wire which is held together to rod by few velcro straps and insulation tape. Also, Coil is not used for any bands above 20m. Anytime, I can convert it to elevated radial resonant system with right lengths as well. 

When I first checked SWR with my analyzer, wire was fully extended to the top of rod and resonance was at around 6.9Mhz with coil in circuit. I then reduced wire length ~0.5 meter lower and adjusted the coil winding to get resonance at around 7.1 Mhz 1.05:1 ish and almost flat from 7.01 to 7.2Mhz. 

Then I bypassed the coil to check the 14Mhz band which was found to be below 1.5:1. I could have tuned 14Mhz first then used coil to tune 7Mhz band, but for now, its good for me!. 

Happy with this experiment. I will be trying it at few places in near future.

Here is a short video of this setup and few photos.

27 turn loading coil is wound on a 2inch PVC pipe former with 1.6mm enameled copper wire. 

When the Coil is  removed from the PVC pipe, it slightly expands to ~55mm diameter. I then used few pieces of blank PCB material(without copper traces) and glued it at two places to hold the shape. 

Youtube link is as follows: https://youtu.be/T8sd8qcXF_M

What is the difference between AHVD and vertical? : 

AHVD is as name suggests, asymmetric vertical hatted dipole. In this system, one leg is longer than others normally by a factor of 1.5:1 ratio. i.e. vertical leg of the dipole is approximately 1.5 times lengthier than horizontal legs. Horizontal leg is for capacitive loading and hence the name "hatted" (hat is at the bottom instead of at the top here).

Vertical has two popular varieties, with elevated or ground mounted radials. AHVD may seem similar to elevated vertical, however, traditional elevated radial system is of almost similar length as of vertical radiator. I have not done any study of practical signal strength difference between two, as I did not had both of these at the same time. However, I feel both above have their merits and draw back being sometimes one may feel elevated legs/radials are obstructing and they require tuning carefully to a band.

Ground mounted  vertical requires many radials as possible, and efficiency depends on soil condition a lot more than elevated one. However, because the radials need not be of quarter wave, it has advantage of carrying bunch of wires and laying on ground.