# Patch Antenna theory, Cech language translation in English and German

• Hi,

in the forum I found several times a reference to a Cech article (e.g

# Computer analysis of dual band dish feed (G0MJW, PA3FYM, M0EYT). Part 1 and 2 –S Band).

Unfortunately no translation was found anywhere. Here a section out of the original text:

I couldn´t find the complete original text. Nevertheless, the most interesting part is written here. Therefore I tried a translation into English and German as it could be of interest here in the forum. I am not a translator and my knowledge in Cech language is limited especially in microwave wording.

English version:

... (Picture 4.4).

Introducing irregularities to the form of a patch results in a degradation of the original mode. By this process it is possible

to generate two modi (#1 and #2) which are orthogonal to each other (Pic. 4.5). The suitable irregular segment shall shift the

frequency in such a way that at the operating frequency f0 both modi have equal amplitude, but a phase difference of

90 degree. This way, the target will be met to generate circular polarization. With the frequency shift at the quiescent

point f0, the relationship of the two axes deteriorates drastically, but the match remains acceptable, normally.

Picture 4.4: Layout of the modified segments and the single feeder point of the patch including circular polarization:

(a) round patch, (b) square patch

Picture 4.5: Layout of the resonant modi and circular polarization

4.3 Circular Polarization with a Round Patch

With a round patch a circular polarization could be obtained, by generating two different resonant modi. This depends on

the shape of the patch. Basically it is a question of the dimensions of the pach to generate a different resonant mode from the original one. At the working frequency between the two modi, a circular wave will come into existence.

My interpretation of this text leads to the result that the optimum S11 curve will be one dip, only, at the working frequency f0. Both amplitudes are added to form one maximum. At this point circular polarization exists. Left and right of it elliptical polarization will be met.

German version:

... (Bild 4.4).

Die Herstellung von Unregelmäßigkeiten in der Form eines Patchs führt zu einer Degeneration des originalen Modus.

Daraus lassen sich zwei Modi (#1 und #2) herstellen, welche aufeinander orthogonal sind (Bild 4.5). Das passende Störungs-

segment muß die Frequenz so verstimmen, daß auf der Arbeitsfrequenz f0 beide Modi die gleichen Amplituden besitzen,

jedoch mit einer Phasenverschiebung von 90 Grad. Damit erfüllt sich die Bedingung für die Entstehung einer

Zirkularpolarisation. Mit der Frequenzverschiebung im Arbeitspunkt f0, verschlechtert sich das Achsverhältnis wesentlich,

aber die Anpassung bleibt normalerweise akzeptabel.

Bild 4.4: Anordnung der Fehlersegmente und die Einpunkteinspeisung der Patches mit Zirkularpolarisation: (a) runder Patch

Bild 4.5: Layout der Resonanzmodi und Zirkularpolarisation

4.3 Zirkularpolarisation beim runden Patch

Beim runden Patch läßt sich die Zirkularpolarisation dadurch erreichen, daß zwei Resonanzmodi unter der Patchplatte entstehen.

Solch eine Einstellung beruht auf der Form des Patchs. Grundsätzlich handelt es sich um die Schaffung von Abmessungen

des Patches, auf dem sich ein anderer Resonanzmodus als ursprünglich ausbilded. Auf der Frequenz zwischen den beiden

Resonanzmodi, entsteht ein zirkulare Welle.

Aus dieser Beschreibung entnehme ich, daß die korrekte Abstimmung einer Patchantenne optimal möglichts auf einen Resonanzdip erfogen sollte, da sich in diesem Resonanzpunkt beide Wellen addieren und sich die beste Entkopplung ergibt.

Nur hier ist eine zirkulare Welle. Links und rechts wird sie elliptisch.

Was ist eure Meinung?

Vy 73,

George,

DL2KP

Edited once, last by dl2kp ().

• George,

here you may find the original thesis of Aleš MARŠÁLEK, work supervised by non less than OM Mirek, OK2AQK, a.k.a. OK2AQ:

Containing this splendid account of autophasing patch antennas, it is highly recommended bedtime reading for all illuminati-wannabes.

After mastering the above principles, you can easily extend the concept to multiphase solutions, my personal favourite being three phase radiators, and all the way down to HF too

Michael, OH2AUE

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"If you have data, you have something, if you do not, you have nothing." (Bengt Hultqvist, SK 24.02.2019)

• The obvious "turnstile patch" aside, here is something totally new to think about, RHCP at the left and LHCP at the right, no confusion intended:

I bought a couple of each and tested them for ellipticity and matching. They perform very well for such seemingingly simple radiatiors. Several could also be easily configured in a phased array or just use one for illuminating a prime focus dish of suitable f/D.

I am still at odds on how the current and phase distributions appear as a function of time (propaging wave), but they actually do work.

And pretty well at that. Most low cost patches on the market suffer from production repeatability issues.

It seems to me that this patch design is actually a kind of travelling wave antenna and somewhat like a flat/short helix. You can even determine the polarization handedness (chirality) from the path feedpoint.

Amazing things. As I do cannot afford a 3D electromagnetics simulator, this patch design makes me want to attempt scaling to 70 cm and make some field probe measurements with my VNA homebrew optical transducer

Michael, OH2AUE

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"If you have data, you have something, if you do not, you have nothing." (Bengt Hultqvist, SK 24.02.2019)

Edited 2 times, last by oh2aue ().

• Hi Michael, I would like to experiment with them. What is the exact diameter of the Flytrons circle? Distance to the reflector area? Looks like they used a square reflector, not a circular one.