**Efficiency of the 60m Roomcap
Antenna**

Measured was made of the antenna on the frequency of 5.315
MHz with a

radiator of size 1m x 1m grid, installed on the car.

There was used a VNA instrument, measured at a SWR 2.62, and
found

the bandwidth: 96 KHz (Q = 55.3).

The capacity of the radiator was measured: 59 pF.

Then, instead of the room capacity, a small air capacitor of
59 pF used.

Here a bandwidth of 12.8 KHz (Q = 414) measured.

With these values follows the __Calculation:__

__ __

__ __ Rtot = Xl x Q = 508 x 55.3 = 28'092 Ohm

Rv = Xl x Q = 508 x 414 = 210'312 Ohm

Rs = (Rv x Rtot) / (Rv - Rtot) = 32'422 Ohm

Eta (%) = (Rtot / Rs) x 100 = (28092/32422) x 100 = **87.5
% Efficiency**

** **

** **__Explication:__

__ __The measuring corresponds to the measuring of the
40m Roomcap,

while here a varylink with 7.5 cm diameter is used.

At the 40m Roomcap was used a 5 cm diamater varylink.

The description and derivation of the formulas is found
here:

Internet link: analyse-e
http://hb9abx.no-ip.biz/analyse-e.htm

The full construction guide is available from me.

Email = felix-abx (at) gmx.ch

Felix Meyer, HB9ABX 9th.January, 2017